DENISON MINES CORP. TECHNICAL REPORT ON A MINERAL … · updated in a NI 43101 Technical Report dated June 17, 2014 (the 2014 Phoenix Report)- and authored by William E. Roscoe, Ph.D.,

November 25, 2015

RPA Inc. T55 University Ave. Suite 501 I Toronto, ON, Canada M5J 2H7 I + 1 (416) 947 0907 www.rpacan.com

DENISON MINES CORP.

TECHNICAL REPORT ON A MINERALRESOURCE ESTIMATE FOR THEWHEELER RIVER PROPERTY,EASTERN ATHABASCA BASIN,NORTHERN SASKATCHEWAN, CANADA

NI 43-101 Report

Qualified Persons:William E. Roscoe, Ph.D., P.Eng.Mark B. Mathisen, C.P.G.

Report Control Form Document Title Technical Report on a Mineral Resource Estimate for the

Wheeler River Property, Eastern Athabasca Basin, Northern Saskatchewan, Canada

Client Name & Address

Denison Mines Corp. 1100 - 40 University Avenue Toronto, ON, Canada M5J 1T1

Document Reference

Project #2534

Status & Issue No.

FINAL Version

Issue Date November 25, 2015 Lead Author William E. Roscoe

Mark B. Mathisen

(Signed) (Signed)

Peer Reviewer David A. Ross

(Signed)

Project Manager Approval William E. Roscoe

(Signed)

Project Director Approval Deborah A. McCombe

(Signed)

Report Distribution Name No. of Copies Client RPA Filing 1 (project box)

Roscoe Postle Associates Inc.

55 University Avenue, Suite 501 Toronto, ON M5J 2H7

Canada Tel: +1 416 947 0907

Fax: +1 416 947 0395 [email protected]

mailto:[email protected]

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Page i Denison Mines Corp. – Wheeler River Property, Project #2534 Technical Report NI 43-101 – November 25, 2015

TABLE OF CONTENTS PAGE

1 SUMMARY ...................................................................................................................... 1-1 Executive Summary ....................................................................................................... 1-1 Technical Summary ....................................................................................................... 1-4

2 INTRODUCTION ............................................................................................................. 2-1

3 RELIANCE ON OTHER EXPERTS ................................................................................. 3-1

4 PROPERTY DESCRIPTION AND LOCATION ................................................................ 4-1

5 ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE AND PHYSIOGRAPHY ............................................................................................................... 5-1

6 HISTORY ........................................................................................................................ 6-1 Prior ownership .............................................................................................................. 6-1 Exploration and Development History ............................................................................ 6-1 Previous Mineral Resource Estimates ........................................................................... 6-6 Past Production ............................................................................................................. 6-7

7 GEOLOGICAL SETTING AND MINERALIZATION .......................................................... 7-1 Regional Geology .......................................................................................................... 7-1 Local and Property Geology........................................................................................... 7-5 Alteration ..................................................................................................................... 7-16 Structural Geology ....................................................................................................... 7-17 Mineralization .............................................................................................................. 7-19

8 DEPOSIT TYPES ............................................................................................................ 8-1

9 EXPLORATION ............................................................................................................... 9-1 Ground Geophysical Surveys ........................................................................................ 9-1 Airborne Surveys ........................................................................................................... 9-3

10 DRILLING .................................................................................................................... 10-1 Phoenix Deposit Exploration Drilling ............................................................................ 10-2 Gryphon Deposit Exploration Drilling ........................................................................... 10-7 Drill Hole Surveying ................................................................................................... 10-10 Radiometric Logging of Drill Holes ............................................................................. 10-10 Sampling Method and Approach ................................................................................ 10-13 Core Recovery and Use of Probe Data ...................................................................... 10-15

11 SAMPLE PREPARATION, ANALYSES AND SECURITY ............................................ 11-1 Geochemical Sample Preparation Procedures............................................................. 11-1 Analytical Methods ....................................................................................................... 11-3 Quality Assurance and Quality Control ........................................................................ 11-7

12 DATA VERIFICATION ................................................................................................. 12-1 Site Visit and Core Review........................................................................................... 12-1 Database Validation ..................................................................................................... 12-1

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Page ii Denison Mines Corp. – Wheeler River Property, Project #2534 Technical Report NI 43-101 – November 25, 2015

Independent Verification of Assay Table ...................................................................... 12-2 Disequilibrium .............................................................................................................. 12-2

13 MINERAL PROCESSING AND METALLURGICAL TESTING ..................................... 13-1

14 MINERAL RESOURCE ESTIMATE ............................................................................. 14-1 Drill Hole Database ...................................................................................................... 14-2 Geological Interpretation and 3D Solids ....................................................................... 14-7 Bulk Density ............................................................................................................... 14-18 Statistics .................................................................................................................... 14-22 Variography – Continuity Analysis.............................................................................. 14-29 Interpolation Parameters ............................................................................................ 14-30 Block Model Validation ............................................................................................... 14-38 Cut-off Grade ............................................................................................................. 14-41 Classification ............................................................................................................. 14-44 Mineral Resource Estimate ........................................................................................ 14-47

15 MINERAL RESERVE ESTIMATE ................................................................................ 15-1

16 MINING METHODS ..................................................................................................... 16-1

17 RECOVERY METHODS .............................................................................................. 17-1

18 PROJECT INFRASTRUCTURE .................................................................................. 18-1

19 MARKET STUDIES AND CONTRACTS ...................................................................... 19-1

20 ENVIRONMENTAL STUDIES, PERMITTING, AND SOCIAL OR COMMUNITY IMPACT ......................................................................................................................................... 20-1

21 CAPITAL AND OPERATING COSTS .......................................................................... 21-1

22 ECONOMIC ANALYSIS............................................................................................... 22-1

23 ADJACENT PROPERTIES .......................................................................................... 23-1

24 OTHER RELEVANT DATA AND INFORMATION ........................................................ 24-1

25 INTERPRETATION AND CONCLUSIONS .................................................................. 25-1

26 RECOMMENDATIONS................................................................................................ 26-1

27 REFERENCES ............................................................................................................ 27-1

28 DATE AND SIGNATURE PAGE .................................................................................. 28-1

29 CERTIFICATE OF QUALIFIED PERSON .................................................................... 29-1

LIST OF TABLES PAGE

Table 1-1 Mineral Resource Estimate as of September 25, 2015 (100% Basis) ............... 1-2 Table 4-1 Land Tenure Details ......................................................................................... 4-2 Table 6-1 Exploration and Development History ............................................................... 6-6 Table 6-2 SRK Mineral Resource Estimate as of November 17, 2010 .............................. 6-6 Table 6-3 RPA Mineral Resource Estimate as of December 31, 2012 (100% Basis) ........ 6-7

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Page iii Denison Mines Corp. – Wheeler River Property, Project #2534 Technical Report NI 43-101 – November 25, 2015

Table 10-1 Wheeler River Property Drilling Statistics ...................................................... 10-1 Table 10-2 Phoenix Drilling Statistics .............................................................................. 10-4 Table 10-3 Gryphon Drilling Statistics ............................................................................. 10-9 Table 10-4 Gryphon Deposit Mineral Intersections ....................................................... 10-10 Table 11-1 Quality Control Sample Allocations ............................................................. 11-16 Table 14-1 Mineral Resource Estimate for the Wheeler River Project as of September 25, 2015 (100% Basis) ........................................................................................................... 14-1 Table 14-2 Vulcan Database Records ............................................................................ 14-2 Table 14-3 Summary of Gryphon Wireframe Models .................................................... 14-14 Table 14-4 Descriptive Statistics of Gryphon Uranium Assay by Domain ...................... 14-22 Table 14-5 Statistics of Gryphon Capped Assays by Domain ....................................... 14-23 Table 14-6 Basic Statistics of Grade and GxD Composites for Phoenix Deposit Zones A and B HG and LG Domains ............................................................................................ 14-26 Table 14-7 Descriptive Statistics of Gryphon Deposit Composite Uranium Assay by Domain ....................................................................................................................................... 14-29 Table 14-8 Phoenix and Gryphon Block Model Parameters and Variables ................... 14-30 Table 14-9 Phoenix Deposit Block Model Interpolation Parameters .............................. 14-33 Table 14-10 Gryphon Block Model Estimation Parameters ........................................... 14-37 Table 14-11 Volume Comparison for Wireframe and Blocks by Domain ....................... 14-38 Table 14-12 Statistics of Block Grades Compared to Composite Grades by Domain - Phoenix .......................................................................................................................... 14-39 Table 14-13 Statistics of Block Grades Compared to Composite Grades by Domain - Gryphon.......................................................................................................................... 14-40 Table 14-14 Phoenix Deposit Indicated Mineral Resource Sensitivity to Cut-off Grade . 14-41 Table 14-15 Gryphon Deposit Cut-off Grade Calculation .............................................. 14-43 Table 14-16 Gryphon Deposit Inferred Mineral Resource Sensitivity to Cut-off Grade .. 14-43 Table 14-17 Mineral Resource Estimate for the Wheeler River Project as of September 25, 2015 ............................................................................................................................... 14-48

LIST OF FIGURES PAGE

Figure 4-1 Wheeler River Project Location Map ................................................................ 4-4 Figure 4-2 Wheeler River Property Map ............................................................................ 4-5 Figure 7-1 Regional Geology and Uranium Deposits ........................................................ 7-3 Figure 7-2 Simplified Geological Map of Athabasca Basin ................................................ 7-4 Figure 7-3 Schematic Section of the Athabasca and Basement Rock Types .................... 7-8 Figure 7-4 Wheeler River Property Basement Geology .................................................. 7-10 Figure 7-5 Schematic of the Quartzite Ridge .................................................................. 7-13 Figure 7-6 WS Reverse Fault and the Phoenix Deposit .................................................. 7-14 Figure 7-7 Gryphon Basement Geology .......................................................................... 7-15 Figure 8-1 Schematic of Unconformity Type Uranium Deposit .......................................... 8-3 Figure 8-2 Illustration of Various Models for Unconformity Type Deposits of the Athabasca Basin .................................................................................................................................. 8-4 Figure 10-1 Phoenix Deposit Drill Hole Location Map ..................................................... 10-6 Figure 10-2 Gryphon Deposit 2013 Drill Hole Location Map ........................................... 10-8 Figure 10-3 Calibration Curve for Geiger-Mueller SN 3818 Probe ................................ 10-13 Figure 11-1 USTD1 Analyses ......................................................................................... 11-8 Figure 11-2 USTD2 Analyses ......................................................................................... 11-9

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Page iv Denison Mines Corp. – Wheeler River Property, Project #2534 Technical Report NI 43-101 – November 25, 2015

Figure 11-3 USTD3 Analyses ......................................................................................... 11-9 Figure 11-4 USTD4 Analyses ....................................................................................... 11-10 Figure 11-5 USTD5 Analyses ....................................................................................... 11-10 Figure 11-6 USTD6 Analyses ....................................................................................... 11-11 Figure 11-7 Blank Sample Analyses Results ................................................................ 11-12 Figure 11-8 Field Duplicate Analyses ........................................................................... 11-13 Figure 11-9 BLA4 Analyses .......................................................................................... 11-15 Figure 11-10 U3O8 DNC Versus ICP-OES Assay Values .............................................. 11-17 Figure 12-1 WR-318 Radiometric vs. Assay % U3O8 Values ........................................... 12-4 Figure 12-2 WR-334 Radiometric vs. Assay % U3O8 Values ........................................... 12-5 Figure 12-3 WR-273 Radiometric vs. Assay % U3O8 Values ........................................... 12-5 Figure 12-4 WR-435 Radiometric vs. Assay % U3O8 Values ........................................... 12-6 Figure 12-5 WR-548 Radiometric vs. Assay % U3O8 Values ........................................... 12-6 Figure 12-6 WR-525 Radiometric vs. Assay % U3O8 Values ........................................... 12-7 Figure 12-7 WR-401 Radiometric vs. Assay % U3O8 Values ........................................... 12-7 Figure 12-8 WR-306 Radiometric vs. Assay % U3O8 Values ........................................... 12-8 Figure 12-9 WR-539 Radiometric vs. Assay % U3O8 Values ........................................... 12-8 Figure 12-10 WR-560 Radiometric vs. Assay % U3O8 Values ......................................... 12-9 Figure 12-11 WR-573D1 Radiometric vs. Assay % U3O8 Values .................................... 12-9 Figure 12-12 WR-582 Radiometric vs. Assay % U3O8 Values ....................................... 12-10 Figure 12-13 WR-584B Radiometric vs. Assay % U3O8 Values .................................... 12-10 Figure 14-1 Phoenix Deposit Zones A and B Drill Hole Locations ................................... 14-4 Figure 14-2 Phoenix Deposit Zone A Basement Drill Hole Locations .............................. 14-5 Figure 14-3 Gryphon Deposit Drill Hole Locations .......................................................... 14-6 Figure 14-4 Phoenix Deposit Zone A Typical Cross Section Including WR-435 with HG and LG Domains ..................................................................................................................... 14-9 Figure 14-5 Phoenix Deposit Zone A Typical Cross Section Including WR-525 with HG and LG Domains ................................................................................................................... 14-10 Figure 14-6 Phoenix Deposit Zone A Typical Cross Section Including WR-401 with HG and LG Domains ................................................................................................................... 14-11 Figure 14-7 Phoenix Deposit Zone B Typical Cross Section Including WR-294 with HG and LG Domains ................................................................................................................... 14-12 Figure 14-8 Phoenix Deposit Zone A-Basement Longitudinal Section .......................... 14-13 Figure 14-9 Gryphon Deposit Geologic Cross Section Schematic of Mineralization ...... 14-16 Figure 14-10 Gryphon Deposit Wireframes at Drill INDEX LINE 5000 Cross Section (Looking NE) .................................................................................................................. 14-17 Figure 14-11 Logarithmic Plot of Dry Bulk Density Versus Uranium Grade - Phoenix Deposit ....................................................................................................................................... 14-19 Figure 14-12 Dry Bulk Density Wax Versus Dry/Wet Methods - Phoenix Deposit ......... 14-20 Figure 14-13 Logarithmic Plot of Dry Bulk Density Versus Uranium Grade - Gryphon Deposit ........................................................................................................................... 14-21 Figure 14-14 Zone A1 Log Normal Probability and Histogram Plot – Gryphon Deposit . 14-24 Figure 14-15 Grade Composite Histograms for Phoenix Deposit Zones A and B HG and LG Domains ......................................................................................................................... 14-27 Figure 14-16 Grade vs. Density Plots for Phoenix Deposit Zones A and B HG and LG Domains ......................................................................................................................... 14-28 Figure 14-17 Phoenix Deposit Zone A 3D Block Model ................................................ 14-34 Figure 14-18 Phoenix Deposit Zone A 3D HG Domain Block Model ............................. 14-35 Figure 14-19 Gryphon Deposit Block Model Domains A1 and C1 (Looking NORTH) .... 14-36 Figure 14-20 Phoenix Indicated Mineral Resource Tonnes and Grade at Various Cut-off Grades ........................................................................................................................... 14-42

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Page v Denison Mines Corp. – Wheeler River Property, Project #2534 Technical Report NI 43-101 – November 25, 2015

Figure 14-21 Gryphon Inferred Mineral Resource Tonnes and Grade at Various Cut-off Grades ........................................................................................................................... 14-44 Figure 14-22 Phoenix Deposit Zone B Block Model Showing Phoenix Deposit Inferred and Indicated Resources ....................................................................................................... 14-46

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Page 1-1 Denison Mines Corp. – Wheeler River Property, Project #2534 Technical Report NI 43-101 – November 25, 2015

1 SUMMARY EXECUTIVE SUMMARY Roscoe Postle Associates Inc. (RPA) was retained by Denison Mines Corp. (Denison) on

behalf of the Wheeler River Joint Venture to prepare an independent Technical Report on the

Phoenix and Gryphon deposits, located within the Wheeler River Property (the Property) in

northern Saskatchewan, Canada. The Mineral Resources for the Phoenix deposit were

updated in a NI 43-101 Technical Report dated June 17, 2014 (the 2014 Phoenix Report)

and authored by William E. Roscoe, Ph.D., P.Eng., of RPA. The Phoenix Mineral Resources

have not changed since the 2014 Phoenix Report and are included in this report.

The purpose of this Technical Report is to support the disclosure of the initial Mineral

Resource estimate for the Gryphon deposit and update the total Mineral Resource estimate

for the Property. This Technical Report conforms to NI 43-101 Standards of Disclosure for

Mineral Projects.

Denison owns 60% and is the operator of the Wheeler River Joint Venture. Cameco

Corporation (Cameco) owns 30% and JCU (Canada) Exploration Company Limited (JCU)

owns the remaining 10%. The Property consists of 19 contiguous claims in northern

Saskatchewan. Denison’s additional assets include a 22.5% interest in the McClean Lake

mill in Saskatchewan, one of three licensed uranium mills in Canada.

The updated Mineral Resource estimate for the Wheeler River Property is summarized in

Table 1-1.

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TABLE 1-1 MINERAL RESOURCE ESTIMATE AS OF SEPTEMBER 25, 2015 (100% BASIS)

Denison Mines Corp. – Wheeler River Property

Deposit Category Tonnes Grade (% U3O8)

Contained Metal (million lb U3O8)

Phoenix Indicated 166,400 19.14 70.2 Phoenix Inferred 8,600 5.80 1.1 Gryphon Inferred 834,000 2.31 43.0 Total Inferred 842,600 2.37 44.1

Notes:

1. CIM definitions were followed for classification of Mineral Resources. 2. Mineral Resources for Phoenix are reported above a cut-off grade of 0.8% U3O8, which is based on

internal Denison studies and a price of US$50 per lb U3O8. 3. Mineral Resources for Gryphon are reported above a cut-off grade of 0.2% U3O8, which is based on RPA

assumptions and a price of US$50 per lb U3O8. 4. High grade composites are subjected to a high grade search restriction without capping at Phoenix. 5. High grade mineralization was capped at 30% with no search restrictions at Gryphon. 6. Bulk density is derived from grade using a formula based on 196 measurements at Phoenix and 65

measurements at Gryphon. 7. Numbers may not add due to rounding.

CONCLUSIONS Drilling at the Property from 2008 to 2014 discovered and delineated the Phoenix uranium

deposit at the intersection of the Athabasca sandstone basal unconformity with a regional

fault zone, the WS fault, and graphitic pelite basement rocks. Drilling from 2014 to 2015

discovered the basement hosted Gryphon uranium deposit located approximately three

kilometres northwest of the Phoenix deposit.

The Phoenix deposit consists of two separate lenses known as zone A and zone B located at

the Athabasca unconformity approximately 400 m below surface within a one kilometre long,

northeast trending mineralized corridor. Both lenses contain a higher grade core within a

lower grade mineralized envelope and extend southeastward from the WS fault along the

unconformity. Some mineralization also occurs on the northwest side of the WS fault but

commonly at a slightly lower elevation. In addition to zones A and B, a new domain of

uranium mineralization below and adjacent to zone A has been identified in basement rocks

(zone A basement) and included in this report.

Mineral Resources for Phoenix, based on 196 diamond drill holes totalling 89,835 m, were

estimated by RPA. Indicated Resources total 166,400 t at 19.13% U3O8 containing 70.2

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million lb U3O8. Inferred Resources total 8,600 t at 5.80% U3O8 containing 1.1 million lb

U3O8.

Mineralization at the Gryphon Deposit, located three kilometres northwest of Phoenix, occurs

in basement rocks approximately 200 m beneath the Athabasca sandstone unconformity. In

this area, the unconformity drops to the northwest in a series of reverse fault offsets.

Cumulative offset is approximately 60 m of vertical displacement over 250 m across strike.

Basement rocks are Wollaston Group gneisses that dip moderately to the southeast and

consist of an upper graphitic pelite unit overlying a quartzite/pegmatite assemblage which

overlies a lower graphitic pelite unit followed by a basal pegmatite. To date, the

mineralization is hosted in fault zones at the base of the upper graphitic pelite and within the

lower graphitic pelite. The faults are assumed to dip moderately to the southeast,

conformable with the bedding and foliation in the basement rocks.

Mineral Resources for Gryphon, based on 55 diamond drill holes totalling 40,041 m, were

estimated by RPA. Inferred Resources total 834,000 t at 2.31% U3O8 containing 43.0 million

lbs U3O8. In RPA’s opinion, additional infill drilling on 25 m profile spacing or wedging off of

current drill holes would be needed to bring the Inferred Mineral Resource into Indicated

status.

In RPA’s opinion, a Preliminary Economic Assessment (PEA) could be carried out on the

Phoenix and Gryphon deposits combined.

RECOMMENDATIONS In the third quarter of 2015, the Wheeler River Joint Venture commenced a PEA. At the end

of the PEA, a review of the project will be completed with recommendations for next steps.

Should the project proceed into pre-feasibility, initial work will focus on environmental

baseline studies, engineering field programs, and engineering studies.

The Wheeler River Joint Venture plans to continue exploration on the Property in 2016, with

emphasis expected to be on the areas to the northeast and southwest of Gryphon, as well as

other targets on the Property. In addition, an infill drilling program may be undertaken on the

Gryphon deposit to bring the Inferred Mineral Resource into Indicated status if warranted by

positive PEA results.

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RPA has reviewed the preliminary plans for 2016 and concurs with the program planned for

the Wheeler River Joint Venture in 2016. Denison’s 2016 budget for the Wheeler River Joint

Venture has not been disclosed yet, but RPA expects exploration expenditures to be in the

order of C$10 million. Contingent on results of this program and the PEA, a second phase

will consist of infill drilling at Gryphon, environmental baseline studies, engineering field

programs, and engineering studies as part of the initiation of a pre-feasibility study. RPA

expects that the cost of the second phase program will be in the order of C$3 million.

If further drilling is completed at Gryphon, RPA recommends that Denison continue to collect

additional bulk density data to increase the confidence of estimated densities of the entire

grade range.

TECHNICAL SUMMARY

PROPERTY DESCRIPTION AND LOCATION The Property, comprising the Phoenix and Gryphon uranium deposits, is located in the

eastern Athabasca Basin, approximately 600 km north of Saskatoon, 260 km north of La

Ronge, and 110 km southwest of Points North Landing, in northern Saskatchewan. The

centre of the Property is located approximately 35 km north-northeast of the Key Lake mill

and 35 km southwest of the McArthur River mine, which are operated by Cameco. The

Gryphon deposit is located three kilometres northwest of the Phoenix deposit.

LAND TENURE The Property comprises 19 contiguous claims held as a Joint Venture among Denison

(60%), Cameco (30%), and JCU (10%) with no back-in rights or royalties that need to be

paid. RPA understands that Denison has all the required permits to conduct the proposed

work on the Property. RPA is not aware of any other significant factors or risks that may

affect access, title, or the right or ability to perform work on the Property.

ACCESS AND INFRASTRUCTURE Access to the Property is by road, helicopter, or fixed wing aircraft from Saskatoon. Vehicle

access to the Property is by Highway 914, which terminates at the Key Lake mill. The ore

haul road between the Key Lake and McArthur River operations traverses the eastern part of

the Property. An older access road, the Fox Lake Road, between Key Lake and McArthur

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River provides access to most of the northwestern side of the Property. Gravel and sand

roads and drill trails provide access by either four-wheel-drive or all-terrain-vehicle to the rest

of the Property.

La Ronge is the nearest commercial/urban centre where most exploration supplies and

services can be obtained. Two airlines offer daily, scheduled flight services between

Saskatoon and La Ronge.

Field operations are currently conducted from Denison’s Wheeler River camp, three

kilometres southwest of the Phoenix deposit and four kilometers south of the Gryphon

deposit. The camp, which is operated by Denison, provides accommodation for up to forty

exploration personnel. Fuel and miscellaneous supplies are stored in existing warehouse

and tank facilities at the camp. The site generates its own power. Abundant water is

available from the numerous lakes and rivers in the area.

HISTORY The Property was staked on July 6, 1977, due to its proximity to the Key Lake uranium

discoveries, and was vended into an agreement on December 28, 1978 among AGIP

Canada Ltd. (AGIP), E&B Explorations Ltd. (E&B), and Saskatchewan Mining Development

Corporation (SMDC), with each holding a one-third interest. On July 31, 1984, all parties

divested a 13.3% interest and allowed Denison Mines Limited, a predecessor company to

Denison, to earn a 40% interest. On December 1, 1986, E&B allowed PNC Exploration

(Canada) Co. Ltd. (PNC) to earn a 10% interest from one-half of its 20% interest. In the

early 1990s, AGIP sold its 20% interest to Cameco, which was a successor to SMDC. In

1996, Imperial Metals Corporation, a successor to E&B, sold an 8% interest to Cameco and

a 2% interest to PNC. Participating interests in 2004 were Cameco (48%), JCU (a successor

to PNC, 12%), and Denison (40%).

In late 2004, Denison entered into an agreement to earn a further 20% interest by expending

$7 million within six years. When the earn-in obligations were completed, the participating

interests were Denison 60%, Cameco 30%, and JCU 10%. Since November 2004, Denison

has been the operator of the Wheeler River Joint Venture.

Except for the years 1990 to 1995, exploration activities comprising airborne and ground

geophysical surveys, geochemical surveys, prospecting and diamond drilling have been

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carried out on the Property continuously from 1978 to the present. The Phoenix deposit was

discovered by drilling in 2008 and the Gryphon deposit, by drilling in 2014.

GEOLOGY AND MINERALIZATION The Phoenix and Gryphon uranium deposits are located near the southeastern margin of the

Athabasca Basin in the southwest part of the Churchill Structural Province of the Canadian

Shield. The Athabasca Basin is a broad, closed and elliptically shaped cratonic basin with

dimensions of 425 km (east-west) by 225 km (north-south). The bedrock geology of the area

consists of Archean and Paleoproterozoic gneisses unconformably overlain by up to 1,500 m

of flat-lying, unmetamorphosed sandstones and conglomerates of the mid-Proterozoic

Athabasca Group. The Property is located near the transition zone between two prominent

litho-structural domains within the Precambrian basement; the Mudjatik Domain to the west

and the Wollaston Domain to the east.

The mineralization in the Phoenix deposit occurs at depths of 390 m to 420 m at the

Athabasca sandstone unconformity with the underlying lower Proterozoic Wollaston Group

metasedimentary rocks. The Phoenix deposit is interpreted to be structurally controlled by

the northeast-southwest trending (55º azimuth) WS shear fault which dips 55º to the

southeast. Mineralization and alteration have been traced over a strike length of

approximately one kilometre. Since discovery hole WR-249 was drilled in 2008, 253 drill

holes have reached the target depth, delineating two distinct zones (A and B) of high-grade

mineralization and the smaller zone A basement.

Mineralization at the Gryphon deposit is hosted by highly deformed crystalline basement

rocks approximately 200 m beneath the Athabasca sandstone unconformity. In this area, the

unconformity drops approximately 60 m to the northwest in a series of reverse fault offsets.

The Gryphon mineralization is hosted in fault zones within graphitic pelite units that dip

moderately to the southeast.

The Phoenix and Gryphon deposits are Athabasca Basin unconformity associated uranium

deposits. Uranium mineralization is in the form of the oxide uraninite/pitchblende (UO2).

Grades of all accompanying metals are low, particularly in comparison with several

sandstone-hosted deposits, which can have very high values for nickel, cobalt, and arsenic.

Alteration at Phoenix and Gryphon is typical of unconformity associated deposits in the

Athabasca Basin.

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EXPLORATION Following the discovery of the Phoenix deposit in 2008, Denison, as operator of the Wheeler

River Joint Venture, completed additional geophysical surveys and drilling programs every

year from 2009 to 2015.

Geophysical surveys included 67.6 line-km of DC Resistivity/Induced Polarization (DC/IP) in

2009, 76.2 km of ground electromagnetic (EM) surveying in 2010, and large amounts of

additional DC/IP surveying in each of 2011 (120.6 line-km), 2012 (48.2 line-km), 2013 (128.5

line-km), 2014 (62 line-km), and 2015 (149.5 line-km). In 2013, a 990 line-km helicopter

borne versatile time-domain electromagnetic (VTEM)-magnetic-radiometric survey was

conducted over the Property.

DRILLING Diamond drilling is the principal method of exploration and delineation of uranium

mineralization after initial geophysical surveys on the Property. Drilling can generally be

conducted year round.

Diamond drilling during the period 2009 to 2012 was primarily focussed on definition drilling

at the Phoenix deposit, although numerous holes were also completed on other targets on

the Property. Diamond drilling during the period 2013 to 2014 was primarily focussed on

exploration for additional lenses or deposits, but also included a component of infill

delineation drilling on zone A to move the Inferred Mineral Resource into the Indicated

category, and to extend the higher grade portions of the Phoenix deposit. During the latter

part of 2014 and 2015, drilling was primarily focussed on exploration of the Gryphon deposit.

Since 1979, a total of 641 diamond drill holes and 84 reverse circulation (RC) drill holes

totalling 302,127 m have been completed within the Property, of which 263 drill holes

totalling 123,749 m of diamond drilling have delineated the Phoenix trend and 69 holes

totalling 44,083 m have delineated the Gryphon deposit. Of the 263 drill holes at Phoenix,

196 (141 at zone A, 55 at zone B) drill holes totalling 89,835 m (64,491 m at zone A, 25,344

m at zone B) have tested zones A and B. Of the 69 drill holes at Gryphon, 55 drill holes

totalling 40,041 m have delineated the deposit.

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All drill holes on the Property were logged with a radiometric probe to measure the natural

gamma radiation, from which an indirect estimate of uranium content can be made. The

gamma probes were calibrated and radiometric estimates of eU3O8 % were used in the drill

hole database where core recovery was less than 80%, which involves approximately 23% of

the drill holes used for resource estimation at Phoenix. The resource estimation at Gryphon

is based on 100% assay data.

Well established drilling industry practices were used in all of the drilling programs.

SAMPLING, ANALYSES, AND DATA VERIFICATION Drill core from the Phoenix and Gryphon deposits was photographed, logged, marked for

sampling, split, bagged, and sealed for shipment by Denison personnel at their field logging

facility. All samples for assay or geochemical analysis were transported by Denison

personnel to the Saskatchewan Research Council Geoanalytical Laboratories (SRC) in

Saskatoon, Saskatchewan. Uranium analyses were carried out at SRC which is accredited

by the Standards Council of Canada as an ISO/IEC 17025 Laboratory for Mineral Analysis

Testing and is also accredited ISO/IEC 17025:2005 for the analysis of U3O8.

To compare results of two different analytical methods, at two separate laboratories, Denison

sent one in every 25 samples to the SRC’s Delayed Neutron Counting (DNC) laboratory, a

separate facility located at SRC Analytical Laboratories in Saskatoon.

Analytical standards were used to monitor analytical precision and accuracy, and field

standards were used as an independent monitor of laboratory performance. Six uranium

assay standards have been prepared for use in monitoring the accuracy and precision of

uranium assays received from the laboratory. Denison employed a lithological blank

composed of quartzite to monitor the potential for contamination during sampling,

processing, and analysis. Core duplicates were obtained by collecting a second sample of

the same material, through splitting the original sample, or other similar technique, and were

submitted as an independent sample. Duplicates were typically collected at a minimum rate

of one per 20 samples in order to obtain a collection rate of 5%. In RPA’s opinion, the

sample preparation and analytical methods are standard in the industry. Results of the

quality assurance and data verification efforts demonstrate that the data are of sufficient

quality for Mineral Resource estimates.

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RPA reviewed and verified the resource database used to estimate the Mineral Resources

for both the Phoenix and Gryphon deposits. The verification included a review of the quality

assurance and quality control (QA/QC) methods and results, verifying assay certificates

against the database assay table, standard database validation tests, and two site visits.

Denison has developed and documented several QA/QC procedures and protocols for all

exploration projects operated by Denison. RPA reviewed Denison’s procedures and

protocols and considers them to be reasonable and acceptable.

MINERAL RESOURCES RPA has estimated Mineral Resources for the Property based on results of several surface

diamond drilling campaigns from 2008 to 2015. The Denison drill hole database and Mineral

Resource estimate have been audited by RPA. Table 1-1 summarizes the Phoenix and

Gryphon Mineral Resource estimates, of which Denison’s share is 60%. The effective date

of the Mineral Resource estimate is September 25, 2015.

Denison has interpreted the geology, structure, and mineralization at Phoenix using data

from 196 diamond drill holes and developed three dimensional (3D) wireframe models which

represent 0.05% U3O8 grade envelopes. For each of zone A and zone B, the wireframes

contain a higher grade (HG) domain within an envelope of lower grade (LG) material,

resulting in four main domains. A fifth domain has been added for the current estimate

consisting of a small zone of structurally controlled basement mineralization at the north end

of zone A.

Denison has interpreted the geology, structure, and mineralization at Gryphon using data

from 55 diamond drill holes and developed 3D wireframe models which represent 0.05%

U3O8 grade envelopes and minimum thickness of two metres. The wireframes were

subsequently clipped to include only minimum intersections greater than 0.2% U3O8.

Mineralized wireframes were developed for a total of eight stacked lenses, of which two

accounted for most of the Mineral Resources.

Based on 196 dry bulk density determinations for Phoenix and 65 for Gryphon, Denison

developed a formula relating bulk density to grade which was used to assign a density value

to each assay. Bulk density values were used to weight grades during the resource

estimation process and to convert volume to tonnage.

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Capping of high grade assays at the Phoenix deposit was considered to be unnecessary

because of the use of high grade domains and the lack of apparent high grade outliers. The

influence of high grade values, however, was restricted during the block estimation process.

High grade assays at the Gryphon deposit were capped at 30% prior to compositing. Assays

at both Phoenix and Gryphon were composited to one metre lengths.

Composited uranium grade times density (GxD) values and density (D) values were

interpolated into each block model domain using an inverse distance squared (ID2) algorithm

for each mineralized domain. Domain boundaries were treated as hard boundaries, so that

composites from any given domain could not influence block grades in other domains. Block

grade was derived from the interpolated GxD value divided by the interpolated D value for

each block. Block tonnage was based on volume times the interpolated D value.

The Mineral Resources for the Phoenix deposit are classified as Indicated and Inferred

based on drill hole spacing and apparent continuity of mineralization. Most of the Mineral

Resource at Phoenix is classified as Indicated, with the balance classified as Inferred. All of

the Mineral Resource at Gryphon is classified as Inferred.

The Phoenix and Gryphon deposit block models were validated by comparison of domain

wireframe volumes with block volumes, visual comparison of composite grades with block

grades, comparison of block grades with composite grades used to interpolate grades, and

comparison with estimation by a different method.

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2 INTRODUCTION Roscoe Postle Associates Inc. (RPA) was retained by Denison Mines Corp. (Denison) on

behalf of the Wheeler River Joint Venture to prepare an independent Technical Report on the

Phoenix and Gryphon deposits, located within the Wheeler River Property (the Property) in

northern Saskatchewan, Canada. The Mineral Resources for the Phoenix deposit were

updated in a NI 43-101 Technical Report dated June 17, 2014 (the 2014 Phoenix Report)

and authored by William E. Roscoe, Ph.D., P.Eng., of RPA. The Phoenix Mineral Resources

have not changed since the 2014 Phoenix Report and are included in this report.

The purpose of this Technical Report is to support the disclosure of the initial Mineral

Resource estimate for the Gryphon deposit and update the total Mineral Resource estimate

for the Property. This Technical Report conforms to NI 43-101 Standards of Disclosure for

Mineral Projects.

Denison is a Toronto-based mining company focused on uranium exploration and

development in Canada, Mongolia, Mali, Namibia, and Zambia. Denison is listed on the

Toronto Stock Exchange (symbol DML) and on the New York Stock Exchange MKT (symbol

DNN).

Denison owns 60% of the Wheeler River Joint Venture and is the operator, Cameco

Corporation (Cameco) owns 30%, and JCU (Canada) Exploration Company Limited owns

the remaining 10%. The Property comprises 19 contiguous claims in northern

Saskatchewan totalling 11,720 ha.

In addition, Denison has a 22.5% interest in the McClean Lake mill in Saskatchewan, one of

the three licensed conventional uranium mills in Saskatchewan. Denison’s primary

exploration properties are located in the eastern side of the Athabasca Basin, along the

same geological terrain that hosts all of Canada’s currently producing uranium mines, which

account for 16% of global production.

SOURCES OF INFORMATION This report was prepared by William E. Roscoe, Ph.D., P.Eng., RPA Chairman Emeritus and

Principal Geologist, and Mark B. Mathisen, C.P.G., RPA Senior Geologist. Both are

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Qualified Persons in accordance with NI 43-101. Dr. Roscoe last visited the Property on

June 16, 2014 and held discussions with technical personnel in RPA’s Toronto office on May

4, 2014 in connection with the 2014 Phoenix Report. For the Gryphon Deposit, a site visit

was carried out by Mr. Mathisen from March 23 to 25, 2015. Mr. Mathisen visited active drill

sites and reviewed logging and sampling methods with Denison personnel. RPA has had

prior involvement with the Property in 2014 and much of the information in this report is

summarized from the 2014 Phoenix Report.

Specific activities completed by RPA include:

• Site visit and validation of data available for the resource estimate.

• Determination of correlation between assays and radiometric logs used for U3O8 grade estimation.

• Compilation of new Gryphon resource models.

• Geological interpretation of mineralized zones.

• Audit of drill hole database and assay certificates.

• Mineral Resource estimation and classification.

• Verification of Mineral Resource estimate.

Discussions were held with following Denison personnel who have contributed to the

geological, geochemical, geophysical, environmental, and resource estimation sections of

this Technical Report:

• Steve Blower, P.Geo., Vice President Exploration

• Lawson Forand, P.Geo., Exploration Manager

• Clark Gamelin, P.Geo., Senior Project Geologist

• Chad Sorba, P.Geo., Senior Project Geologist

• Dale Verran, Pr.Sci.Nat., Technical Director

All geological and sampling data were provided by Denison. Drilling and geological data

were generated from May 2008 to August 2015. All field activities are currently managed by

Denison.

Dr. Roscoe and Mr. Mathisen share responsibility for all sections of this report.

The documentation reviewed, and other sources of information, are listed at the end of this

report in Section 27 References.

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LIST OF ABBREVIATIONS Units of measurement used in this report conform to the Metric system. All currency in this

report is Canadian dollars (C$) unless otherwise noted.

a annum kWh kilowatt-hour A ampere L litre bbl barrels lb pound btu British thermal units L/s litres per second °C degree Celsius m metre C$ Canadian dollars M mega (million); molar cal calorie m2 square metre cfm cubic feet per minute m3 cubic metre cm centimetre µ micron cm2 square centimetre MASL metres above sea level d day µg microgram dia diameter m3/h cubic metres per hour dmt dry metric tonne mi mile dwt dead-weight ton min minute % eU3O8 equivalent grade U3O8 µm micrometre °F degree Fahrenheit mm millimetre ft foot mph miles per hour ft2 square foot MVA megavolt-amperes ft3 cubic foot MW megawatt ft/s foot per second MWh megawatt-hour g gram oz Troy ounce (31.1035g) G giga (billion) oz/st, opt ounce per short ton Gal Imperial gallon ppb part per billion g/L gram per litre ppm part per million Gpm Imperial gallons per minute psia pound per square inch absolute g/t gram per tonne psig pound per square inch gauge gr/ft3 grain per cubic foot RL relative elevation gr/m3 grain per cubic metre s second ha hectare st short ton hp horsepower stpa short ton per year hr hour stpd short ton per day Hz hertz t metric tonne in. inch tpa metric tonne per year in2 square inch tpd metric tonne per day J joule US$ United States dollar k kilo (thousand) USg United States gallon kcal kilocalorie USgpm US gallon per minute kg kilogram V volt km kilometre W watt km2 square kilometre wmt wet metric tonne km/h kilometre per hour wt% weight percent kPa kilopascal yd3 cubic yard kVA kilovolt-amperes yr year kW kilowatt

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3 RELIANCE ON OTHER EXPERTS This report has been prepared by Roscoe Postle Associates Inc. (RPA) for Denison Mines

Corp. The information, conclusions, opinions, and estimates contained herein are based on:

• Information available to RPA at the time of preparation of this report, • Assumptions, conditions, and qualifications as set forth in this report, and • Data, reports, and other information supplied by Denison Mines Corp. and other

third party sources.

For the purpose of this report, RPA has relied on ownership information provided by

Denison. RPA has not researched property title or mineral rights for the Wheeler River

Project and expresses no opinion as to the ownership status of the property.

Except for the purposes legislated under provincial securities laws, any use of this report by

any third party is at that party’s sole risk.

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4 PROPERTY DESCRIPTION AND LOCATION PROPERTY LOCATION The Wheeler River Property, comprising the Phoenix and Gryphon uranium deposits, is

located in the eastern Athabasca Basin, approximately 600 km north of Saskatoon, 260 km

north of La Ronge, and 110 km southwest of Points North Landing, in northern

Saskatchewan (Figure 4-1). The centre of the Property is located approximately 35 km

northeast of the Key Lake mill and 35 km southwest of the McArthur River mine, which are

operated by Cameco. The Property straddles the boundaries of NTS map sheets 74H-5, 6,

11, and 12. The UTM coordinates of the approximate centre of the Property are 475,000E

and 6,370,000N (NAD83, Zone 13N).

The Gryphon deposit is located approximately three kilometres northwest of Denison’s

Phoenix deposit, also within the Property. The Phoenix deposit was discovered in 2008 and

contains a significant uranium Mineral Resource, which was last updated in the 2014

Phoenix Report. The Phoenix deposit is at the unconformity between the Athabasca Basin

and basement rocks, approximately 400 m below surface, whereas the Gryphon deposit is

located in the basement rocks, approximately 60 m to 350 m below the unconformity surface.

LAND TENURE The Property comprises 19 contiguous claims held as a joint venture among Denison (60%),

Cameco (30%), and JCU (Canada) Exploration Co. Ltd. (10%) with no back-in rights or

royalties that need to be paid. The claims are shown in Figure 4-2 and listed in Table 4-1.

Denison has been the operator of the Property since November 10, 2004.

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TABLE 4-1 LAND TENURE DETAILS Denison Mines Corp. – Wheeler River Property

Disposition # Area

(ha) Annual

Assessment ($)

Excess Credit ($)

Years Protected

S-97677 322 8,050 152,950 19 S-97678 335 8,375 159,125 19 S-97690 1,087 27,175 516,325 19 S-97894 246 6,150 116,850 19 S-97895 314 7,850 149,150 19 S-97896 356 8,900 169,100 19 S-97897 524 13,100 248,900 19 S-97907 352 8,800 167,200 19 S-97908 1,619 40,475 769,025 19 S-97909 1,036 25,900 492,100 19 S-98339 362 9,050 171,950 19 S-98340 250 6,250 118,750 19 S-98341 802 20,050 380,950 19 S-98342 1,016 25,400 482,600 19 S-98343 362 9,050 171,950 19 S-98347 939 23,475 446,025 19 S-98348 951 23,775 451,725 19 S-98349 540 13,500 256,500 19 S-98350 307 7,675 145,825 19

MINERAL RIGHTS In Canada, natural resources fall under provincial jurisdiction. In the Province of

Saskatchewan, the management of mineral resources and the granting of exploration and

mining rights for mineral substances and their use are regulated by the Crown Minerals Act

and The Mineral Tenure Registry Regulations, 2012, that are administered by the

Saskatchewan Ministry of the Economy. Mineral rights are owned by the Crown and are

distinct from surface rights.

In Saskatchewan, a mineral claim does not grant the holder the right to mine minerals. A

Saskatchewan mineral claim in good standing can be converted to a lease upon application.

Leases have a term of 10 years and are renewable. A lease proffers the holder with the

exclusive right to explore for, mine, work, recover, procure, remove, carry away, and dispose

of any Crown minerals within the lease lands which are nonetheless owned by the Province.

Surface facilities and mine workings are therefore located on Provincial lands and the right to

use and occupy lands is acquired under a surface lease from the Province of Saskatchewan.

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A surface lease carries a maximum term of 33 years, and may be extended as necessary, to

allow the lessee to develop and operate the mine and plant and thereafter to carry out the

reclamation of the lands involved.

ROYALTIES AND OTHER ENCUMBRANCES RPA is not aware of any royalties due, back-in rights, or other encumbrances by virtue of any

underlying agreements.

PERMITTING RPA is not aware of any environmental liabilities associated with the Property.

RPA understands that Denison has all the required permits to conduct the proposed work on

the Property. RPA is not aware of any other significant factors and risks that may affect

access, title, or the right or ability to perform the proposed work program on the Property.

WHEELER RIVERPROPERTY

Provincial Capital

Legend:

Trans-Canada Highway

Other Populated Areas

Major Road

International Boundary

Provincial Boundary

0 50 250

Kilometres

100 150 200

November 2015 Source: Natural Resources Canada.

Wheeler River Property

Location Map

Denison Mines Corp.

Northern Saskatchewan, Canada

Figure 4-1

4-4

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S-98343

S-98340

S-98341

S-9

8349

S-98342

S-98347

S-9

8350

S-98348

S-97896

S-97897 S-97907

S-97908

S-97909

S-98339

S-97678

S-97677

S-97894

S-97690

S-97895

465,000 mE 485,000 mE480,000 mE475,000 mE470,000 mE 490,000 mE6,3

75,0

00 m

N6,3

80,0

00 m

N

6,3

65,0

00 m

N

6,3

70,0

00 m

N

6,3

60,0

00 m

N

6,3

75,0

00 m

N6,3

80,0

00 m

N6,3

65,0

00 m

N6,3

70,0

00 m

N6,3

60,0

00 m

N

490,000 mE

460,000 mE

465,000 mE 480,000 mE475,000 mE470,000 mE460,000 mE

Wheeler River Camp Location

Overhead Powerline

Fox Lake Road

McArthur Haul Road

Wheeler River J.V.Property

PHOENIX DEPOSITS(Discovered 2008)

GRYPHON ZONE(Discovered 20 )14

LAKE

Tayl

or

Bay

McD

OU

GA

LL

LA

KE

MOON

LAKE

RUSSELL0 1

Kilometres

UTM Projection WGS 84-13N

2 3 4 5

N

November 2015 Source: 5Denison Mines Corp., 201 .


Wheeler River Property Map

Denison Mines Corp.


Figure 4-2

4-5

ww

w.rp

acan

.co

m

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5 ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE AND PHYSIOGRAPHY ACCESSIBILITY Access to the Property and deposits is by road, helicopter, or fixed wing aircraft from

Saskatoon. Vehicle access to the Property is by Highway 914, which terminates at the Key

Lake mill. The ore haul road between the Key Lake and McArthur River operations lies

within the eastern part of the Property. An older access road, the Fox Lake Road, between

Key Lake and McArthur River provides access to most of the northwestern side of the

Property. Gravel and sand roads and drill trails provide access by either four-wheel-drive or

all-terrain-vehicle to the rest of the Property.

CLIMATE The climate is typical of the continental sub-arctic region of northern Saskatchewan, with

temperatures ranging from +32°C in summer to -45°C in winter. Winters are long and cold,

with mean monthly temperatures below freezing for seven months of the year. Winter snow

pack averages 70 cm to 90 cm. Field operations are possible year round with the exception

of limitations imposed by lakes and swamps and the periods of break-up and freeze-up.

Freezing of surrounding lakes, in most years, begins in November and break-up occurs

around the middle of May. The average frost-free period is approximately 90 days.

Average annual total precipitation for the region is approximately 450 mm, of which 70% falls

as rain, with more than half occurring from June to September. Snow may occur in all

months but rarely falls in July or August. The prevailing annual wind direction is from the

west with a mean speed of 12 km/hr.

LOCAL RESOURCES AND INFRASTRUCTURE La Ronge is the nearest commercial/urban centre where most exploration supplies and

services can be obtained. Two airlines offer daily, scheduled flight services between

Saskatoon and La Ronge (located approximately 600 km and 260 km respectively, south of

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the Property). Most company employees are on a two week-in and two week-off schedule.

Contractor employees are generally on a longer work schedule.

As noted previously, the Property is well located with respect to all weather roads and the

provincial power grid. Most significantly, the operating Key Lake mill complex, owned and

operated by Cameco, is approximately 35 km south of the Property.

Field operations are currently conducted from Denison’s Wheeler River camp, four

kilometres south of Gryphon and three kilometres southwest of Phoenix (Figure 4-2). The

camp, which is operated by Denison, provides accommodations for up to forty exploration

personnel. Fuel and miscellaneous supplies are stored in existing warehouse and tank

facilities at the camp. The site generates its own power. Abundant water is available from

the numerous lakes and rivers in the area.

PHYSIOGRAPHY The Property is characterized by a relatively flat till plain with elevations ranging from 477 m

to 490 MASL. Throughout the area, there is a distinctive northeasterly trend to landforms

resulting from the passage of Pleistocene glacial ice from the northeast to the southwest.

The topography and vegetation at the Property are typical of the taiga forested land common

to the Athabasca Basin area of northern Saskatchewan.

The area is covered with overburden from 0 m to 130 m in thickness. The terrain is gently

rolling and characterized by forested sand and dunes. Vegetation is dominated by black

spruce and jack pine, with occasional small stands of white birch occurring in more

productive and well-drained areas. Lowlands are generally well drained but can contain

some muskeg and poorly drained bog areas with vegetation varying from wet, open, non-

treed vistas to variable density stands of primarily black spruce as well as tamarack

depending on moisture and soil conditions. Lichen growth is common in this boreal

landscape mostly associated with mature coniferous stands and bogs.

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6 HISTORY PRIOR OWNERSHIP The Wheeler River Property was staked on July 6, 1977, due to its proximity to the Key Lake

uranium discoveries, and was vended into an agreement on December 28, 1978 among

AGIP Canada Ltd. (AGIP), E&B Explorations Ltd. (E&B), and Saskatchewan Mining

Development Corporation (SMDC), with each holding a one-third interest. On July 31, 1984,

all parties divested a 13.3% interest and allowed Denison Mines Limited, a predecessor

company to Denison, to earn a 40% interest. On December 1, 1986, E&B allowed PNC

Exploration (Canada) Co. Ltd. (PNC) to earn a 10% interest from one-half of its 20% interest.

In the early 1990s, AGIP sold its 20% interest to Cameco, which was a successor to SMDC.

In 1996, Imperial Metals Corporation, a successor to E&B, sold an 8% interest to Cameco

and a 2% interest to PNC. Participating interests in 2004 were Cameco 48%, JCU 12% (a

successor to PNC), and Denison 40%.

In late 2004, Denison entered into an agreement to earn a further 20% interest by expending

$7 million within six years. When the earn-in obligations were completed, the participating

interests were Denison 60%, Cameco 30%, and JCU 10%. Since November 2004, Denison

has been the operator of the Wheeler River Joint Venture.

EXPLORATION AND DEVELOPMENT HISTORY Excluding years 1990 to 1994, exploration activities comprising airborne and ground

geophysical surveys, geochemical surveys, prospecting and diamond drilling have been

carried out on the Wheeler River Property continuously from 1978 to the present.

Subsequent to the discovery of the Key Lake mine in 1975 and 1976, the Key Lake

exploration model (Dahlkamp and Tan 1977) has emphasized the spatial association

between uranium deposition at, immediately above, or immediately below the unconformity

with graphitic pelite units in the basement subcrop under the basal Athabasca sandstone.

The graphitic pelite units are commonly intensely sheared and are highly conductive in

contrast to the physically more competent adjoining rock types that include semipelite,

psammite, meta-arkose, or granitoid gneiss. From the late 1970s to the present, the Key

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Lake model has been useful in discovering blind uranium deposits throughout the Athabasca

Basin (Jefferson et al. 2007), although it is worth noting that the vast majority of

electromagnetic (EM) conductors are unmineralized.

Following the Key Lake exploration model, EM techniques were the early geophysical

methods of choice for the Wheeler River Property area during the period 1978 to 2004 and

more than 152 line-km of EM conductors have been delineated on the Property. These

conductive units have been delineated to depths of 1,000 m, through the quartz-rich

Athabasca Group sandstones that are effectively transparent from an EM perspective.

These conductors or conductor systems were assigned a unique designation and follow-up

exploration drilling successfully identified several zones of uranium mineralization.

In 1982, AGIP discovered the MAW Zone. This alteration system contains rare earth element

(REE) mineralization in a structurally disrupted zone which extends from the unconformity to

the present surface. There is no evidence of uranium mineralization. The REE

mineralization contains yttrium values greater than 2.0%, boron values up to 2.5%, and total

rare earth oxide (REO) up to 8.1%.

In 1985, SMDC (predecessor to Cameco) drilled ZK-02 to test a moderate UTEM conductor

axis in a previously unexplored area along the K-North conductor, which is now known as

Gryphon. The drill hole intersected several zones of hydrothermal alteration in the

sandstone indicating the conductor was likely overshot and thus lay grid east of ZK-02.

In 1986, SMDC intersected uranium mineralization associated with Ni-Co-As sulphides at the

unconformity in the M Zone (DDH ZM-10, 0.79% U3O8 over 5.75 m), and also discovered

uranium mineralization at the O Zone, which is associated with a 72 m vertical unconformity

offset. The O Zone basement-hosted mineralization graded 0.048% U3O8 over 0.9 m at

378.8 m in drill hole ZO-02.

In 1988, Cameco drilled ZK-04 and ZK-06 on the same drill section to test for the UTEM

conductor and follow up on the sandstone alteration. Hole ZK-04 was drilled 120 m grid east

of ZK-02, and hole ZK-06 was drilled 35 m grid west of ZK-04. In drill hole ZK-04, a major

basement fault structure was intersected from 572.6 m to 603.2 m, with associated strong

hydrothermal alteration and a 9.8 m radioactive zone from 581.7 m to 591.5 m. Assays from

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drill hole ZK-04 returned 0.08% U3O8 over 2.4 m at 580.0 m and 0.19% U3O8 over 2.3 m at

587.7 m. Moderate to strong hydrothermal alteration and associated fault gouges and

fracturing continued to the end of the hole at 631 m (approximately 112 m below the

unconformity surface).

The third hole on this section, ZK-06, was drilled up-dip of ZK-04 in an attempt to locate the

up-dip and unconformity extension of the mineralization intersected in drill hole ZK-04. Two

significant zones of weak mineralization and elevated radioactivity were intersected within a

12.1 m zone, 11 m to 50 m below the unconformity. ZK-06 returned 0.17% U3O8 over 7.7 m

at 532.0 m and 0.06% U3O8 over 4.4 m at 564.6 m. Intense alteration, fracturing and faulting

in the sandstone was noted as well as alteration and structure extending approximately 50 m

into the basement rocks. At this time, ZK-06 was thought to have intersected the

unconformity target and no follow-up was conducted for several years.

From 1995 to 1997, exploration by Cameco identified strong alteration and illitic and dravitic

geochemical enrichment associated with major structures in both the sandstone and the

basement and a significant unconformity offset associated with the “quartzite ridge” which

had been delineated as a result of drilling the Q conductor system.

In 1998, further drilling was carried out at the Q Zone and also at the R Zone (the Phoenix

deposit area). At the R Zone, two drill holes were abandoned in sandstone due to quartz

dissolution (desilicification). The possibility that this sandstone alteration might be of

significance was not emphasized at the time.

In 1999, a geological setting similar to McArthur River’s P2 trend was intersected at the WC

Zone, where faulted graphite-pyrite pelitic gneiss overlay the quartzite ridge. The former

operator (Cameco) noted extensive dravite (boron) alteration in the overlying sandstones.

In 2001, Cameco drilled ZK-23, testing the K1A SWML conductor approximately 250 m grid

east of the ZK-02\ZK-04\ZK-06 drill fence in what is now the Gryphon area. The drill hole

intersected a wide zone of structural disruption within the sandstone 40 m above the

unconformity. The conductive response was explained by a wide zone of moderately

graphitic-pyritic pelitic gneisses. No unconformity or basement mineralization was

intersected and no follow-up drill holes were recommended.

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In 2002, drill hole WR-185 intersected a 175 m unconformity offset along the west contact of

the quartzite ridge. This area was the initial focus of the Wheeler River Joint Venture after

Denison became operator in 2004.

In 2003, 61 shallow reverse circulation (RC) holes were drilled, targeting the

sandstone/overburden interface exploring for alteration zones in the upper sandstone. No

anomalies were detected. Drill hole WR-190A tested the WS UTEM conductor and was

abandoned at 364 m due to deteriorating drilling conditions. This drill hole is located only 90

m from the eventual Phoenix discovery drill hole WR-249. Noticeable desilicification and

bleaching of the sandstone were present, but no noteworthy geochemical anomalies were

identified. A direct current (DC) resistivity survey was also completed to map trends of

alteration within the Athabasca sandstones and underlying basement rocks that might be

related to uranium mineralization.

In November 2004, Denison became operator of the Wheeler River Joint Venture and in

2005 carried out property-wide airborne Fugro GEOTEM EM and Falcon gravity surveys with

five subsequent ground transient EM (TEM) grids completed on GEOTEM anomalies. The

focus for Denison, based on a McArthur River analogy, was the quartzite ridge, particularly

the west, or footwall side of the ridge. Several small regional campaigns were carried out to

test EM conductors located by airborne and ground geophysical surveys.

In 2007, a 154.8 line-km geophysical induced polarization (IP) and magnetotelluric (MT)

survey using Titan 24 DC resistivity technology was undertaken with the prime goals being

the extension of Cameco’s 2003 resistivity survey, surveying of the K and M zones and

exploration of the REA or “Millennium” (WS) zone, which appeared to have attractive

geological features in an underexplored part of the Property. The results showed the

following:

• A very strong resistivity high which delineated the quartzite unit.

• Two strong, well defined resistivity lows both occurring in areas where previous drill holes had been lost in the Athabasca sandstone.

• Well defined resistivity chimneys.

Although 2007 drilling on various 2003 resistivity anomalies did not discover any significant

uranium mineralization, there was some support for the concept that resistivity did “map”

alteration chimneys within the Athabasca sandstone. Alteration chimneys in the Athabasca

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sandstone above the unconformity or basement-hosted uranium mineralization have been

described from almost all Athabasca Basin uranium deposits, following the first thorough

description of their occurrence at the McClean deposits (Saracoglu et al. 1983; Wallis et al.

1984). The chimneys nearly always have a prominent structural component consisting of

broken and rotated sandstone and a high degree of fracturing and brecciation. These

structural features are accompanied by alteration consisting of variable amounts of bleaching

(removal of diagenetic hematite), silicification, desilification, druzy quartz-lined fractures,

secondary hematite, dravite, and/or clay minerals which can cause resistivity anomalies.

During the winter and spring of 2008, the North Grid resistivity survey data was reinterpreted

and three drill targets, A, B, and C were proposed. These targets were well defined

alteration or resistivity chimneys situated close to the hanging wall of the quartzite unit in

areas where previous attempts to drill ground EM conductors (the WS and the REA) had

failed to reach the unconformity. In 2008, drill hole WR-249 led to the discovery of the

Phoenix deposit. Subsequent drilling identified four mineralized zones over a strike length of

more than one kilometre: Phoenix zones A, B, C, and D.

In March 2014, drill hole WR-556 resulted in discovery of the Gryphon deposit, intersecting

uranium mineralization averaging 15.33% U3O8 over 4.0 m in basement graphitic gneiss, 200

m below the sub-Athabasca unconformity. Since the discovery of the Phoenix deposit in

2008, exploration efforts have been focused on the K-Zone trend which exhibits numerous

favourable exploration criteria including basement quartzite and graphitic gneisses,

basement structures, reverse offsets of the unconformity, weak basement hosted

mineralization near the unconformity, and anomalous sandstone geochemistry and

alteration. Historical holes ZK-04 and ZK-06 drilled in the late 1980s, targeting unconformity-

related mineralization, intersected favourable sandstone structure and alteration as well as

alteration and weak mineralization in the basement approximately 35 m below the

unconformity. Follow-up drilling campaigns attempted to locate unconformity mineralization

up dip of the weak basement mineralization. Gryphon deposit discovery drill hole WR-556

was the first to evaluate the down dip projection of these intersections.

Table 6-1 is a summary of the exploration activities that have been carried out on the

Wheeler River Property.

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TABLE 6-1 EXPLORATION AND DEVELOPMENT HISTORY Denison Mines Corp. – Wheeler River Property

Period (Year) Activity 1978-Present The area was previously explored by AGIP and SMDC (Cameco). Since 1978,

several airborne and ground geophysical surveys have defined 152 km of conductor strike length in fourteen conductive zones.

1986-1988 AGIP, SMDC, and Cameco drilled a total of 192 drill holes encountering sub-economic uranium mineralization in the M Zone (1986), O Zone (1986), and K-Zone (1988). Rare earth element mineralization was also discovered in the MAW Zone (1982).

2004 Denison assumed operatorship in 2004 and initially focused on the footwall side of the quartzite ridge (west side of the Property) intersecting sub-economic uranium mineralization.

2008 In 2008, three resistivity targets were drilled leading to the discovery of the Phoenix deposit.

2008-2012 During the period 2008 to 2012, drilling predominantly focused on defining the Phoenix deposits.

2012-Present Subsequent drilling has discovered the Gryphon deposit.

PREVIOUS MINERAL RESOURCE ESTIMATES An initial Mineral Resource estimate was reported for the Phoenix deposit in a NI 43-101

Technical Report by SRK Consulting (Canada) Inc. (SRK) dated November 17, 2010 (Table

6-2). An updated Mineral Resource estimate for the Phoenix deposit zones A and B was

prepared by RPA on December 31, 2012 (Table 6-3). Both previous Mineral Resource

estimates are superseded by the Mineral Resource estimate update in the 2014 Phoenix

Report, which incorporates additional drilling since 2012.

TABLE 6-2 SRK MINERAL RESOURCE ESTIMATE AS OF NOVEMBER 17, 2010 (100% BASIS)

Denison Mines Corp. – Phoenix Deposit

Deposit Classification Tonnes (000)

Lbs U3O8 (000)

Average Grade (%U3O8)

Zone A Indicated 89.9 35,638 18.0 Zone B Inferred 23.8 3,811 7.3

Source: Arseneau and Revering, 2010.

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TABLE 6-3 RPA MINERAL RESOURCE ESTIMATE AS OF DECEMBER 31, 2012 (100% BASIS)

Denison Mines Corp. – Phoenix Deposit

Category Tonnes Grade (% U3O8)

Million lb U3O8

Indicated 152,400 15.6 52.3

Inferred 11,600 29.8 7.6

Source: Roscoe, 2012.

The current report includes the Mineral Resource estimate update documented in the 2014

Phoenix Report as well as the initial Mineral Resource estimate for the Gryphon deposit.

There are no previous Mineral Resource estimates for Gryphon.

PAST PRODUCTION To date, no production has occurred on the Property and the Property is still at the

exploration stage.

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7 GEOLOGICAL SETTING AND MINERALIZATION Portions of the following geological descriptions are taken from internal Denison reports of

2009 to 2015.

REGIONAL GEOLOGY

GENERAL The Phoenix and Gryphon uranium deposits are located near the southeastern margin of the

Athabasca Basin in the southwest part of the Churchill Structural Province of the Canadian

Shield (Figure 7-1). The Athabasca Basin is a broad, closed, and elliptically shaped, cratonic

basin with an area of 425 km (east-west) by 225 km (north-south). The bedrock geology of

the area consists of Archean and Paleoproterozoic gneisses unconformably overlain by up to

1,500 m of flat-lying, unmetamorphosed sandstones and conglomerates of the mid-

Proterozoic Athabasca Group. The Property is located near the transition zone between two

prominent litho-structural domains within the Precambrian basement, the Mudjatik Domain to

the west and the Wollaston Domain to the east.

The Mudjatik Domain is characterized by elliptical domes of Archean granitoid orthogenesis

separated by keels of metavolcanic and metasedimentary rocks, whereas the Wollaston

Domain is characterized by tight to isoclinal, northeasterly trending, doubly plunging folds

developed in Paleoproterozoic metasedimentary rocks of the Wollaston Supergroup (Yeo

and Delaney 2007), which overlie Archean granitoid orthogenesis identical to those of the

Mudjatik Domain.

The area is cut by a major northeast-striking fault system of Hudsonian Age. The faults

occur predominantly in the basement rocks but often extend up into the Athabasca Group

due to several periods of post-depositional movement. Diabase sills and dikes up to 100 m

in width and frequently associated with the faulting have intruded into both the Athabasca

rocks and the underlying basement.

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THE METAMORPHOSED BASEMENT The basement rocks underlying the Athabasca Group have been divided into three tectonic

domains: the Western Craton, the Cree Lake Mobile Zone, and the Rottenstone Complex

(Figures 7-1 and 7-2). The central Cree Lake Mobile Zone is bounded in the northwest by

the Virgin River Shear and Black Lake fault and in the southeast by the Needle Falls Shear

Zone.

The Cree Lake Mobile Zone has been further subdivided into the Mudjatik Domain in the

west half and the Wollaston Domain in the east half. The lithostructural character of these

domains is the result of the Hudsonian Orogeny in which an intense thermo-tectonic period

remobilized the Archean age rocks and led to intensive folding of the overlying Aphebian-age

supracrustal metasedimentary units. The Mudjatik domain represents the orogenic core and

comprises non-linear, felsic, granitoid to gneissic rocks surrounded by subordinate thin

gneissic supracrustal units. These rocks, which have reached granulite-facies metamorphic

grades, usually occur as broad domal features. The adjacent Wollaston Domain consists of

Archean granitoid gneisses overlain by an assemblage of Aphebian pelitic, semipelitic, and

arkosic gneisses, with minor interlayered calc-silicate rocks and quartzites. These rocks are

overlain by an upper assemblage of semipelitic and arkosic gneisses with magnetite bearing

units.

The Wollaston Domain basement rocks are unconformably overlain by flat lying,

unmetamorphosed sandstones, and conglomerates of the Helikian age Athabasca Group,

which is a major aquifer in the area.

THE ATHABASCA GROUP The Athabasca Group sediments consist of unmetamorphosed pink to maroon quartz-rich

pebbly conglomerate and red siltstone of the Read Formation and maroon quartz-pebble

conglomerate, maroon to white pebbly sandstone, sandstone and clay-clast-bearing

sandstone belonging to the Manitou Falls Formation. The sandstone is poorly sorted near

the base, where conglomerates form discontinuous layers of variable thickness. Minor shale

and siltstone occur in the upper half of the succession. Locally, the rocks may be silicified

and indurated or partly altered to clay and softened. In spite of their simple composition,

their diagenetic history is complex (Jefferson et al. 2007). The predominant regional

background clay is dickite.

Phanerozoic

Legend:

Pre-Athabasca Basement

Athabasca Group (Helikian)

Road

Major Shear Zone

Faults

Uranium Deposits

0 25

Kilometres

50 75 100

N

Source: From Saskatchewan Ministry of Energy and Resources, 2009.

November 2015


Regional Geology andUranium Deposits

Denison Mines Corp.


WHEELER RIVER

Figure 7-1

7-3

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WHEELER RIVER

N

November 2015 Source: EXTECH IV.

NOTE: Crystalline basement domains are labeled in bold text. The sub-unit of the Manitou FallsFormation labeled “*” in the legend corresponds to the Warnes and Raible members, whichinterfinger with the Bird (MFb) Member in southern and northern Athabasca Basin respectively.


Simplified Geological Map ofAthabasca Basin

Denison Mines Corp.


Figure 7-2

7-4

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The basin is interpreted to have developed from a series of early northeast-trending fault-

bounded sub-basins that coalesced. The topographic profile of the unconformity suggests a

gentle inward slope in the east, moderate to steep slopes in the north and south, and a

steeper slope in the west.

Subdivisions of the Athabasca Group in the eastern part of the basin (Figure 7-2) include four

members from bottom to top:

• Read Formation (formerly the MFa Member) - a sequence of poorly sorted sandstone and minor conglomerate;

• Bird Member (MFb) - interbedded sandstone and conglomerate distinguished from the underlying MFa and overlying MFc by the presence of at least 1% to 2% conglomerate in beds thicker than 2 cm;

• Collins Member (MFc) - a sandstone with rare clay intraclasts;

• Dunlop Member (MFd) - a fine-grained sandstone with abundant (>1%) clay intraclasts.

QUATERNARY DEPOSITS In the eastern Athabasca Basin, Quaternary glacial deposits up to 100 m thick drape bedrock

topography of ridges, typically associated with granitic gneiss domes, and structurally

controlled valleys (Campbell 2007). At least three tills, locally separated by stratified gravel,

sand, and silt, can be distinguished. The dominant ice-flow direction was southwesterly, but

a late glacial re-advance was southerly in eastern parts of the basin and westerly along its

northern edge.

LOCAL AND PROPERTY GEOLOGY

GENERAL The Wheeler River Property lies in the eastern part of the Athabasca Basin where

undeformed, late Paleoproterozoic to Mesoproterozoic sandstone, conglomerate, and

mudstone of the Athabasca Group unconformably overlie early Paleoproterozoic and

Archean crystalline basement rocks, as described below. The local geology of the Property

is very much consistent with the regional geology described above.

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QUATERNARY DEPOSITS The Property is partially covered by lakes and muskeg, which overlie a complex succession

of glacial deposits up to 130 m in thickness These include eskers and outwash sand plains,

well-developed drumlins, till plains, and glaciofluvial plain deposits (Campbell 2007). The

orientation of the drumlins reflects southwesterly ice flow.

ATHABASCA GROUP Little-deformed late Paleoproterozoic to Mesoproterozoic Athabasca Group strata comprised

of Manitou Falls Formation sandstones and conglomerates unconformably overlie the

crystalline basement and have a considerable range (Figure 7-3) from 170 m over the

quartzite ridge to at least 560 m on the western side of the Property.

The Manitou Falls Formation is locally separated from the underlying Read Formation

(formerly the MFa) by a paraconformity, and comprises three units, the Bird Member (MFb),

Collins Member (MFc), and Dunlop Member (MFd), which are differentiated based on

conglomerates and clay intraclasts (Bosman and Korness 2007) (Ramaekers et al. 2007).

Thickness of the Read Formation ranges from zero metres at the north end of the property

and over parts of the quartzite ridge to 200 m west of the quartzite ridge. The thickness of

the MFb, which is absent above the quartzite ridge, is as much as 210 m in the northeastern

part of the Property. The MFc unit is a relatively clean sandstone with locally scattered

granules or pebbles and one-pebble-thick conglomerate layers interpreted to be pebble lag

deposits. The MFc ranges in thickness from 30 m to 150 m. The MFd is distinguished from

the underlying MFc sandstone by the presence of at least 0.6% clay intraclasts (Bosman and

Korness, 2007). The MFd is up to 140 m thick. The upper 100 m to 140 m of sandstone is

typically buff coloured, medium to coarse grained, quartz rich and cemented by silica,

kaolinite, illite, sericite, or hematite. Alteration of the sandstone is noted along much of the

Phoenix deposit trend.

Variations in thickness of the Athabasca sub-units reflect syndepositional subsidence. In

particular, the thinning of the Read Formation towards the quartzite ridge, and the absence of

both the Read and the MFb Member over much of the ridge, indicate syn-Read uplift of the

latter along the thrust fault that bounds it to the west. This is supported by the Read

Formation sedimentary breccia, interpreted as a fault-scarp talus deposit, along the western

margin of the ridge.

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Although the predominant regional background clay in the Athabasca Basin is dickite, the

Property lies within a broad illite anomaly trending northeasterly from Key Lake through the

McArthur River area (Earle and Sopuck 1989). Chlorite and dravite are also relatively

common in sandstones within this zone.

The topography of the sub-Athabasca basement varies dramatically across the Property.

From elevations of 160 MASL to 230 MASL along its southeastern edge, the unconformity

rises gently to a pronounced northeasterly trending ridge up to 350 MASL, coincident with

the subcrop of a quartzite unit in the crystalline basement. The unconformity surface drops

steeply westward to as low as 30 m below sea level. The unconformity surface is less

variable in the northern part of the Property, ranging from 40 MASL in the northeast to 200

MASL in the northwest.

The west side of the quartzite unit forms a prominent topographic scarp, rising up to 200 m

above the sub-Athabasca unconformity lying to the west. The breccia of angular quartzite

blocks, centimetres to metres in size, with a finely laminated sandstone matrix, has been

intersected in numerous drill holes along the western margin (footwall) of the quartzite ridge.

The quartzite breccia is often intimately associated with uranium mineralization that occurs at

numerous locations along the footwall of the quartzite unit.

The Athabasca sandstones were deposited as a succession of sandy and gravelly braided

river deposits in westward-flowing streams. The conglomerates typical of MFb indicate

increased stream competence, due either to increased flow (i.e., higher precipitation) or

increased subsidence. The mud chips typical of MFd are fragments of thin mud beds

deposited from suspension during the late stages of a flood and re-worked by the next one.

Hence, they indicate intermittent, possibly seasonal, stream flow (Liu et al. 2011).

Quartzite Breccia

Semipelitic withGraphitic Pelite Interlayers

Graphitic Pelite

Quartzite

Granitoid Gneiss

Thrust

Shear

Source: 5Denison Mines Corp., 201 .November 2015


Schematic Section of Athabascaand Basement Rock Types

Denison Mines Corp.


Figure 7-3

7-8

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BASEMENT GEOLOGY Basement rocks beneath the Phoenix and Gryphon deposits are part of the Wollaston

Domain and are comprised of metasedimentary and granitoid gneisses (Figure 7-4). The

metasedimentary rocks belong to the Wollaston Supergroup and include graphitic and non-

graphitic pelitic and semipelitic gneisses, meta-quartzite, and rare calc-silicate rocks together

with felsic and quartz feldspathic granitoid gneisses. These metasedimentary rocks are

interpreted to belong to the Daly Lake Group (Yeo and Delaney 2007). Pegmatitic

segregations and intrusions are common in all units with garnet, cordierite, and sillimanite

occurring in the pelitic strata, indicating an upper amphibolite grade of metamorphism.

Graphitic pelite and quartzite units appear to play important roles in the genesis of Athabasca

Basin unconformity-type deposits (Jefferson et al. 2007). Thus the presence of extensive

subcrop of both units: 18 km of quartzite and 152 line-km of conductors (assumed to be

graphitic pelite), greatly enhances the economic potential of the Wheeler River Property.

All of these rock types have a low magnetic susceptibility. The metasedimentary rocks are

flanked by and intercalated with granitoid gneisses, some of which have a relatively high

magnetic susceptibility. Some of these granitoid gneisses are Archean (Card et al. 2007).

Prior to extensive drilling, interpretation of basement geology depends heavily on airborne

magnetic data combined with airborne and ground EM interpretation.

A “Paleoweathered Zone”, generally from three to ten metres thick, is superimposed on the

crystalline rocks and occurs immediately below the unconformity.



Basement Geology

Denison Mines Corp.


Figure 7-4

7-10

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PHOENIX DEPOSIT The quartzite ridge, an interpreted impermeable and structural barrier forming the footwall to

the mineralization (Figure 7-5), dominates the basement geology at the Phoenix deposit.

The quartzite unit exhibits variable dips from 45º to 75º to the southeast, averaging 50º, and

with an undulating, but generally 055º azimuth. Immediately overlying the quartzite is a

garnetiferous pelite, which varies from seven metres to 60 m in thickness. This generally

competent and unmineralized unit contains distinctive porphyroblastic garnets and acts as a

marker horizon. Overlying the garnetiferous pelite is a graphitic pelite in which the graphite

content varies from 1% to 40%. The graphitic pelite is approximately five metres wide in the

southwest, increases to approximately 70 m near drill hole WR-249, and is 50 m wide at the

northeast extremity. Overlying the graphitic pelite is a massive, non-graphitic, unaltered

pelite unit.

Mineralization at Phoenix generally occurs at the Athabasca unconformity with basement

rocks at depths ranging from 390 m to 420 m. It is interpreted to be structurally controlled by

the northeast-southwest trending (055º azimuth) WS fault which dips 55º to the southeast on

the east side of the quartzite ridge (Figure 7-6).

GRYPHON DEPOSIT The geology of the Gryphon deposit comprises highly deformed crystalline basement rocks

overlain by the relatively undeformed Athabasca sandstone. There are four main sandstone

members of the Manitou Falls (MF) Formation present (from youngest to oldest): MFd, MFc,

MFb, and the Read Formation. At the Gryphon deposit, the thickness of the Athabasca

sandstone cover ranges from 480 m in the southeast to 540 m in the northwest. The

unconformity surface down-drops in a series of steps to the northwest. There is

approximately 60 m of vertical displacement over 250 m across strike.

Four major basement lithological units have been defined at Gryphon (Figure 7-7):

1. Upper Graphite - The Upper Graphite is approximately 110 m thick, occurs furthest stratigraphically to the southeast, and is located in the hanging wall to the mineralization (Upper Lens). This pelitic unit averages 5% to 8% graphite in the upper portion of the unit grading to 10% to 15% in the lower portion of the unit. The unit is well foliated and strikes at 030° dipping at 50° to the southeast.

2. Quartz-Pegmatite Assemblage – Stratigraphically below the Upper Graphite is the Quartz-Pegmatite Assemblage. This unit is approximately 55 m thick and consists of

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several smaller (five metre to nine metre) discrete sub-units of alternating quartzite, quartz-rich pegmatite, pegmatite, and graphitic pelites.

3. Lower Graphite - Underlying the Quartz-Pegmatite Assemblage is the Lower Graphite. This pelitic unit is approximately 15 m thick and averages 10% to 15% graphite. It is well foliated and strikes approximately 030° and dips 45° to the southeast, and is located in the footwall to the Upper Lens mineralization. The Lower Lens mineralization occurs predominantly in this unit.

4. Basal Pegmatite – Stratigraphically below the Lower Graphite is the Basal Pegmatite. This is a pegmatitic to coarse grained granitic unit which is competent and relatively unaltered. Within the Basal Pegmatite, there are multiple minor (one metre to two metre) pelitic intervals.

Phoenix

Gryphon

Quartzite Breccia

Semipelitic withGraphitic Pelite Interlayers

Graphitic Pelite

Quartzite

Granitoid Gneiss

Thrust

Shear



Schematic of theQuartzite Ridge

Denison Mines Corp.


Figure 7-5

7-13

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Elevation(metres above sea level)

0 5

Metres

10 15 20

Pelite

Graphitic Pelite

Garnetiferous Pelite

Quartzite

Shear Zones/Reverse Faults

Low Grade Domain

Phoenix Deposit

High Grade Domain

Source: Denison Mines Corp., 2010.November 2015


WS Reverse Fault Offsetand the Phoenix Deposit

Denison Mines Corp.


Figure 67-

7-14

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Intense sandstone alterationextending into basement

Sub-Athabascaunconformity

1.0 m @ 3.80% U O3 8

(1.0% cut-off)

4.5 m @ 21.2% U O3 8

(1.0% cut-off)

4.0 m @ 15.3% U O3 8

(1.0% cut-off)

Lower LensUpper Lens

NW SE

Legend:

Undifferentiated

Quartzite-Pegmatite

Quartz-Pegmatite

Graphitic Pelite

Sandstone

100 mNovember 2015 Source: Denison Mines Corp., 2015.


Gryphon Basement Geology

Denison Mines Corp.


Figure 7-7

EXT

7-15

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ALTERATION

PHOENIX DEPOSIT At Phoenix, typical unconformity-associated alteration is evident, with a form and nature

similar to other Athabasca Basin unconformity-associated deposits. The sandstones are

altered for as much as 200 m above the unconformity and exhibit varying degrees of

silicification and desilicification (which causes many technical drilling problems), as well as

dravitization, chloritization, and illitization. In addition, hydrothermal hematite and druzy

quartz are present in the sandstone and commonly in the basement rocks. Alteration is

focussed along structures propagating upward from the WS shear and associated splays,

and probably does not exceed 100 m width across strike, making this a relatively narrow

exploration target. The basement in the northeast part of the Phoenix deposit is much more

extensively bleached and clay altered than that to the southwest.

GRYPHON DEPOSIT At Gryphon, alteration in the Athabasca sandstone is quite variable relative to the basement-

hosted mineralization. Directly above Gryphon, the typical alteration sequence above the

unconformity (from surface to the unconformity) is described as follows:

• The upper 100 m to 150 m of sandstone is typically weakly bleached and silicified.

• From approximately 150 m to 440 m, there is no significant alteration. Diagenetic hematite banding is predominant.

• From approximately 440 m to 540 m, variable amounts of alteration occur, which include: o Moderate bleaching, irregular bands of hydrothermal hematite, and patchy

silicification from 490 m to 540 m; o Pervasive silicification and strong dravitic interstitial clays from 515 m to 540 m; o Alternating silicification and desilicification with strong grey alteration, pyrite

development, and dravite rich breccias from 440 m to 540 m.

Sandstone alteration is generally lacking in the hanging wall to the Gryphon mineralization,

although drill holes that intersected an up-faulted basement wedge exhibit moderate

silicification with preserved diagenetic hematite.

Sandstone alteration in the footwall to the Gryphon mineralization consists of isolated

alteration zones with strong bleaching, grey alteration, silicification, and vuggy quartz. The

isolated zones of alteration are assumed to be related to the up-dip projection of the

offsetting basement reverse faults to the southeast.

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Basement alteration exhibits a zoned sequence around mineralization. Directly below the

unconformity, the typical basement paleoweathering profile is preserved. Distal alteration

includes chlorite and sericite. Proximal alteration signatures include weak bleaching, dravite

and druzy quartz formation. Strong clay replacement, pervasive bleaching, and strong

dravite are intimately associated with mineralization. Hematite is also commonly directly

associated with mineralization. Clay alteration mineralogy is dominated by illite with

subordinate kaolinite and chlorite.

STRUCTURAL GEOLOGY The Wheeler River Property lies in the Wollaston Domain, a northeast trending fold and

thrust belt with recumbently folded, early Paleoproterozoic, Wollaston Supergroup

metasedimentary rocks intercalated with granitoid gneisses, some of which are of Archean

age.

Numerous hypothetical structural models have been proposed for the Property. The simplest

model infers a southeast dipping homocline. The presence of mechanically competent

quartzite units, as well as the bounding units of competent granitoid gneiss, together with the

many kilometres of relatively incompetent graphitic pelite provides a situation for the

extensive development of thrust and strike slip/wrench fault tectonics, as well as later normal

faults, at competent/incompetent interfaces (Liu et al. 2011).

PHOENIX DEPOSIT The major structural feature at the Phoenix deposit is the northeast-southwest trending (055º

azimuth) WS reverse fault which dips 55º to the southeast and lies within or at the base of

the graphitic pelite unit along the east edge (hanging wall) of the quartzite ridge, which

appears to have acted as a buttress for thrusting and reverse faulting (Kerr 2010; Kerr et al.

2011). Deformation within the WS fault has occurred partly by ductile shearing, but mainly

by fracturing. A progressive sequence of fracturing is evident by variations in the strike and

dip of slickensides. The principal stress directions responsible for early deformation were

northwest-southeast. A change in the principal stress to an east-west direction led to later

strike-slip movement along the WS shear. Later extension is indicated by northwest-striking

normal faults, which dip steeply to the southwest.

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With the limited data currently available, it appears that the WS structure was most active

during deposition of the Read Formation, however, continued uplift is indicated by westward

tilting of MFc strata along the fault zone. Reverse fault displacements on the western edge

of the quartzite ridge occurred primarily within the highly resistant quartzite unit. Within the

Wheeler River area, vertical offset on the footwall of the quartzite unit can be as much as 60

m; however, at the Phoenix deposit, known vertical displacements in the hanging wall

sequence are always less than 10 m (Figure 7-6).

Mineralization hosted in the lower 15 m of the Athabasca sandstone appears to have some

relationship to the extensions of the WS fault and its various hanging wall splays; hence,

movement on these faults must have continued after deposition of rocks of the Read

Formation and probably the MFd member of the Manitou Falls Formation. The WS fault and

its various interpreted hanging wall splays may have been the main conduit for the

mineralizing fluids. Thus, determining favourable locations along the WS fault, where zones

of long-lived permeability are present, is of critical importance. A northwesterly trending

diabase dyke, probably part of the 1.27 Ga Mackenzie dyke swarm, cuts across the

sandstones on the northern part of the Property.

GRYPHON DEPOSIT Gryphon’s structural setting is characterized by a series of thrust faults displacing the

unconformity upwards to the southeast in multiple steps. These structures are generally

located at the contact between the less competent graphitic pelites and more competent

quartz-pegmatites, pegmatites, and pelitic units. They are described as a combination of

cataclasites and gouges, and intervals of blocky and friable core. The most significant

structures occur at the contact of the upper graphite with the overlying pelite and at the base

of the upper graphite in contact with the underlying quartz-pegmatite. These structures are

termed the Offset Fault and Graphitic Fault (G-Fault) respectively. Mineralization generally

occurs along the G-Fault and its associated subordinate parallel structures where a

shallowing of stratigraphic foliation is observed. Structural data analysis has recorded several

thrust faults with reverse sinistral movement. The shallowing of foliation in combination with

reverse sinistral movement would have provided a zone of dilation, amenable to fluid

movement and uranium precipitation.

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MINERALIZATION

PHOENIX DEPOSIT Uranium mineralization at the Phoenix deposit occurs at the unconformity between

Athabasca sandstones and basement rocks, with the most intense mineralization adjacent to

the WS fault. A minor amount is basement fracture hosted mineralization extending below

the north part of zone A. The Phoenix deposit can be classified as an unconformity-

associated uranium deposit.

Mineralization and alteration have been traced over a strike length of approximately one

kilometre. Since discovery hole WR-249 was drilled in 2008, 253 drill holes have reached

the target depth, delineating two distinct zones (A and B) of high-grade uranium

mineralization.

Mineralization is in the form of the oxide uraninite/pitchblende (UO2). Analyses of all

accompanying metals are low, particularly in comparison with other unconformity or

sandstone-hosted deposits, which can have very high values for nickel, cobalt, and arsenic

(Jefferson et al. 2007). For example, drill hole WR-273, from 406.0 m to 406.5 m, assays

78.3% U3O8, 35 ppm Ni, 30 ppm Co, 0.05 ppm As, 26 ppm Zn, 221 ppm Ag, 284 ppm Cu,

and 9.83% Pb. Some intersections can have significantly higher values for many trace

elements, e.g., drill hole WR-287, from 408.5 m to 409.0 m, assays 26.8% U3O8, 461 ppm Ni,

119 ppm Co, 170 ppm As, 1,070 ppm Zn, 11.2 ppm Ag, 3,200 ppm Cu, and 2.25% Pb.

Average trace metal concentrations for Phoenix assay samples greater than 0.2% U3O8 are

as follows: 576 ppm Ni, 194 ppm Co, 319 ppm As, 2,092 ppm Zn, 18 ppm Ag, 7,176 ppm Cu,

and 9,143 ppm Pb.

GRYPHON DEPOSIT Mineralization at Gryphon occurs 720 m below surface and is centred approximately 220 m

below the sub-Athabasca unconformity. It is within 80 m of the unconformity at its highest

point and 370 m below the unconformity at its deepest point. The deposit consists of a set of

parallel, stacked, elongate lenses that are broadly conformable with the basement geology

and associated with a significant fault zone (G Fault) that separates a thin unit of quartzite

(quartz-pegmatite) from an overlying graphitic pelite (upper graphite). The lenses dip

moderately to the southeast and plunge moderately to the northeast. The deposit is

approximately 450 m long in the plunge direction and 80 m wide across the plunge.

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Thickness is variable and is a function of the number of stacked lenses present, generally

varying between two metres and 20 m. To date, the majority of mineralization is hosted

within two lenses associated with the upper and lower graphite units. Two predominant

types of mineralization have been noted:

• Irregular Fracture Fill - Weak, dark black, low grade mineralization occurring as blebs

and foliation-parallel fracture fill associated with breccias and centimetre-scale dravite veinlets in the Upper Graphite.

• Semi Massive - Black, high grade mineralization associated with hematite and

secondary uranium minerals occurring as lenses and pods parallel to foliation. “Worm rock” textures are also observed.

Mineralization at Gryphon is dominated by uraninite/pitchblende, with very minor coffinite and

trace carnotite, uranophane, and brannerite. Gangue mineralogy is dominated by alteration

clays (illite, kaolinite, chlorite), dravite and hematite with minor relict quartz, biotite, graphite,

zircon, and ilmenite. Only trace concentrations of sulphides are noted comprising galena,

chalcopyrite, and pyrite.

Average trace metal concentrations for Gryphon assay samples greater than 0.2% U3O8 are

as follows: 107 ppm Ni, 62 ppm Co, 30 ppm As, 18 ppm Zn, 14 ppm Ag, 301 ppm Cu, and

3,525 ppm Pb. These concentrations are lower than those recorded for the Phoenix deposit.

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8 DEPOSIT TYPES Both the Phoenix and Gryphon deposits are classified as Athabasca Basin unconformity-

associated uranium deposits. Phoenix straddles the unconformity contact between the

Athabasca Sandstone and underlying basement, while Gryphon is entirely hosted in the

basement rocks. Jefferson et al. (2007) offered the following definition for the geological

environment of this type of mineralization.

Unconformity-associated uranium deposits are pods, veins, and semi-massive replacements

consisting of mainly uraninite, close to basal unconformities, in particular those between

Proterozoic conglomeratic sandstone basins and metamorphosed basement rocks.

Prospective basins in Canada are filled by thin, relatively flat-lying, and apparently

unmetamorphosed but pervasively altered, Proterozoic (~1.8 Ga to <1.55 Ga), mainly fluvial,

red-bed quartzose conglomerate, sandstone, and mudstone. The basement gneiss was

intensely weathered and deeply eroded with variably preserved thicknesses of reddened,

clay-altered, hematitic regolith grading down through a green chloritic zone into fresh rock.

The basement rocks typically comprise highly metamorphosed interleaved Archean to

Paleoproterozoic granitoid and supracrustal gneiss including graphitic metapelite that hosts

many of the uranium deposits. The bulk of the U-Pb isochron ages on uraninite are in the

range of 1,600 Ma to 1,350 Ma. Monometallic, generally basement-hosted uraninite fills

veins, breccia fillings, and replacements in fault zones. Polymetallic, commonly

subhorizontal, semi-massive replacement uraninite forms lenses just above or straddling the

unconformity, with variable amounts of uranium, nickel, cobalt and arsenic; and traces of

gold, platinum-group elements, copper, rare-earth elements, and iron.

The uranium deposits in the Athabasca Basin occur below, across, and immediately above

the unconformity, which can lie within a few metres of surface at the rim of the Basin, to over

1,000 m deep near its centre. The deposits formed by extensive hydrothermal systems

occurring at the unconformity's structural boundary between the older and younger rock

units. Major deep-seated structures are also interpreted to have played an important role in

the hydrothermal process, likely acting as conduits for hot mineralized fluids that eventually

pooled and crystallized in the structural traps provided by the unconformity. One of the

necessary reducing fluids originates in the basement, and flows along basement faults. A

second, oxidizing fluid originates within the Athabasca sandstone stratigraphy and migrates

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through the inherent porosity. In appropriate circumstances, these two fluids mix and

precipitate uranium in a structural trap at or near the basal Athabasca unconformity with

basement rocks.

Two end-members of the deposit model have been defined (Quirt 2003). A sandstone-

hosted egress-type model (e.g., Midwest A) involved the mixing of oxidized, sandstone brine

with relatively reduced fluids issuing from the basement into the sandstone. Basement-

hosted, ingress-type deposits (e.g., Rabbit Lake) formed by fluid-rock reactions between

oxidizing sandstone brine entering basement fault zones and the local wall rock. Both types

of mineralization and associated host-rock alteration occurred at sites of basement–

sandstone fluid interaction where a spatially stable redox gradient/front was present.

Although either type of deposit can be high grade, ranging in grade from a few percent to

20% U3O8, they are not volumetrically large and typically occur as narrow, linear lenses often

at considerable depth. In plain view, the deposits can be 100 m to 150 m long and a few

metres to 30 m wide and/or thick. Egress-type deposits tend to be polymetallic (U-Ni-Co-Cu-

As) and typically follow the trace of the underlying graphitic pelites and associated faults,

along the unconformity. Ingress-type, essentially monomineralic U deposits, can have more

irregular geometry.

Unconformity-type uranium deposits are surrounded by extensive alteration envelopes. In

the basement, these envelopes are generally relatively narrow but become broader where

they extend upwards into the Athabasca group for tens of metres to even 100 m or more

above the unconformity. Hydrothermal alteration is variously marked by chloritization,

tourmalinization (high boron, dravite), hematization (several episodes), illitization,

silicification/desilicification, and dolomitization. Modern exploration for these types of

deposits relies heavily on deep-penetrating geophysics and down-hole geochemistry.

Figures 8-1 and 8-2 illustrate various models for unconformity-type uranium deposits of the

Athabasca Basin. The geology of both the Phoenix and the Gryphon deposits and the

controls on mineralization are sufficiently well understood for Mineral Resource estimation, in

RPA’s opinion.

NOT TO SCALE

November 2015 Source: Denison Mines Corp., 2010.

Denison Mines Corp.


Schematic of UncomformityType Uranium Deposit


Figure 8-1

8-3

ww

w.rp

acan

.co

m

metapelite

Grap

hitic

Paleo

pro

terozo

ic

Metased

imen

tary

schist

and

gneisses

Tonalitic-

gran

iticgneiss

RDRD cgl

Fractures & Dissolution

Paleo valley-

EW

~ 100 mHorizontal

not to scale

Archean to

Paleoproterozoic (>1750 Ma)

metasedimentary, meta-

volcanic and metagranitic

gneiss and schist

Paleoweathering over-

printed by alteration

Unconformity

Paleoproterozoic (<1780 Ma)

Athabasca Group:

quartz arenite, mudstone

and quartz conglomerate

Drumlins and drift

- basement hosted

- uranium

- lower total REEs; HREEs / LREEs >1

- basement hosted

- uranium

- lower total REEs; HREEs / LREEs >1

Mono-

metallic:

Mono-

metallic:

- 'sandstone' hosted

- U, Ni, Co, Cu, As

- high total REEs; HREEs / LREEs ~1

- 'sandstone' hosted

- U, Ni, Co, Cu, As

- high total REEs; HREEs / LREEs ~1

Poly-

metallic:

Poly-

metallic:

Silicifi

edzo

ne

MFb

MFc

MFdSilicifiedThrust /

R Feverse aults

Ath

abasc

aUra

nium MultidisciplinaryS

tud

y

EXTECH IV

Ath

abasc

aUra


tud

y

Ath

abasc

aUra


tud

y

Paleo topo- g.& / or laterStructural

High

Pale

o-

pro

tero

zoic

Meta

quartzite

and

eta

-ark

ose

M

November 2015 Source: From Jefferson et al., 2007.


Illustration of Various Models forUnconformity Type Deposits

of the Athabasca Basin

Denison Mines Corp.


Figure 8-2

8-4

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9 EXPLORATION Since discovery of the McArthur River deposit in 1988, the McArthur River exploration model

(McGill et al. 1993) has emphasized a different association between uranium mineralization

and rock type compared to the earlier Key Lake exploration model. At McArthur River, one

of the most significant rock types in the basement succession is a massive, homogenous,

and competent quartzite. Mechanically, particularly compared to the adjacent layered

members of the basement stratigraphy, the quartzite is extremely competent, and thus exerts

an important control both in basement and post-Athabasca sandstone structural evolution.

Both the footwall and hanging wall contacts of the quartzite unit, particularly where these

contacts involve highly incompetent rocks such as graphitic pelite, are sites of major thrust

and strike-slip faults.

Although these faults are loci for mineralization; the poor conductivity, low magnetic

susceptibilities, and low density values associated with the quartzite limits the effectiveness

of airborne and ground geophysical methods in mapping these basement units especially

when they are covered by hundreds of metres of sandstone. Another noteworthy

characteristic of McArthur River type mineralization is the widespread presence of

hydrothermal dravite, indicating boron addition into the overlying Athabasca sandstone.

Thus, borehole geochemistry and drilling are the primary exploration methods.

With the exception of drilling, exploration work performed on the Property by Denison since

2008 is summarized in this section. Work completed on the Property and its immediate

vicinity by other parties prior to 2008 is summarized in Section 6 of this report. Drilling

completed on the Phoenix and Gryphon deposits is summarized in Section 10 Drilling.

GROUND GEOPHYSICAL SURVEYS

2009 INDUCED POLARIZATION SURVEY Following the discovery of the Phoenix deposit in 2008, Denison as operator of the Wheeler

River Joint Venture, completed DC Resistivity/IP surveys comprising 60.2 line-km in 2009.

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2010 TRANSIENT ELECTROMAGNETIC (TEM) SURVEY During February and March 2010, a geophysical program consisting of 25.2 km of a fixed

loop surface TEM survey and 51.0 km of a step loop TEM survey was completed on three

lines of the previously established 2007 Wheeler River grid. Three lines of step-wise moving

loop (SWML) TEM surveying was completed on three previously defined resistivity

anomalies in attempt to better define any conductive axis associated with graphitic basement

features that could act as conduits for mineralizing events. The resistivity signature located

on L40+00N is known to be associated with the uranium mineralization associated with the

Gryphon deposit.

2011-2012 INDUCED POLARIZATION SURVEY The 2011 exploration program on the Property carried out by Denison included a 120.6 line-

km Titan 24 DC/IP survey. Additional Titan 24 surveying (48.8 line-km) was completed in

2012.

2013 INDUCED POLARIZATION SURVEY In 2013, the Wheeler River Joint Venture completed a 127.0 line-km Titan 24 DC/IP survey

over two areas previously not covered (R North and K West areas)

2014 INDUCED POLARIZATION, GRAVITY AND SWML EM SURVEYS Geophysical exploration in 2014 consisted of the following work, with primary focus being the

K-North area and its close vicinity:

• 46.05 line-km over three lines of infill SWML EM in the K-North area to complete areas previously not covered.

• 43 line-km over two lines of SWML in the WS South area covering areas of interest from the 2013 Titan 24 DC/IP survey.

• 48 line-km of ground gravity covering the O Zone, where historic drilling showed a large unconformity offset with weak uranium mineralization.

• A 52.0 line-km ground gravity survey was carried out in 2014 over the K-North area to test if the unconformity offset seen in drill core could be defined by this method.

• A 67.2 km extension of the 2007 North Titan 24 DC/IP survey to complete the coverage over the K-North area.

• A 3D DC/IP survey to attempt to resolve a 2 km by 2 km geologically/geophysically complex area north of Phoenix zone A.

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2015 INDUCED POLARIZATION SURVEY In 2015, the Wheeler River Joint Venture completed a 149.5 line-km Titan 24 DC/IP survey

over two areas previously not covered (O Zone and the southern parts of the K and Q

Zones).

AIRBORNE SURVEYS 2013 VTEM SURVEY In 2013, a helicopter borne versatile time-domain electromagnetic (VTEM)-magnetic-

radiometric survey was conducted over the Property. The survey comprised 990 line-km at a

300 m line-spacing covering an area of approximately 249 km2. This survey used a larger

loop than previously in an attempt to remove noise that caused difficulties in interpretation of

a previous survey.

.

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10 DRILLING Diamond drilling on the Wheeler River Property is the principal method of exploration and

delineation of uranium mineralization after initial geophysical surveys. Drilling can generally

be conducted year round on the Property. Drill holes on the Property are labelled with a

prefix of the Project name (WR) followed by the hole number.

Since 1979, a total of 641 diamond drill holes and 84 reverse circulation (RC) drill holes

totalling 302,127 m have been completed within the Property (Table 10-1) The following

sections provide details of the holes drilled on the Phoenix and Gryphon deposits.

TABLE 10-1 WHEELER RIVER PROPERTY DRILLING STATISTICS Denison Mines Corp. – Wheeler River Property

Year Company # Diamond Drill

Holes (including wedge holes and re-starts)

# Rotary Drill Holes

Total Drilled (m)

1979 AGIP Canada Ltd. 6 0 2,111 1980 AGIP Canada Ltd. 6 0 1,968 1981 AGIP Canada Ltd. 14 0 5,352 1982 AGIP Canada Ltd. 13 0 4,974 1983 AGIP Canada Ltd. 9 0 2,255 1984 AGIP Canada Ltd. 13 0 2,986 1985 SMDC 13 0 3,395 1986 SMDC 11 0 4,174 1987 SMDC 12 23 6,362 1988 SMDC 12 0 5,882 1989 SMDC 9 0 4,617 1995 Cameco 4 0 1,890 1996 Cameco 5 0 2,544 1997 Cameco 7 0 3,218 1998 Cameco 7 0 3,074 1999 Cameco 3 0 1,263 2001 Cameco 2 0 1,213 2002 Cameco 4 0 2,099 2003 Cameco 4 61 3,470 2004 Cameco 1 0 494 2005 Denison Mines Inc. 12 0 4,837 2006 Denison Mines Inc. 27 0 10,514 2007 Denison Mines Corp. 18 0 6,147

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Year Company # Diamond Drill Holes (including

wedge holes and re-starts)

# Rotary Drill Holes

Total Drilled (m)

2008 Denison Mines Corp. 14 0 6,104 2009 Denison Mines Corp. 43 0 18,950 2010 Denison Mines Corp. 60 0 28,264 2011 Denison Mines Corp. 80 0 38,428 2012 Denison Mines Corp. 58 0 26,810 2013 Denison Mines Corp. 52 0 25,656 2014 Denison Mines Corp. 50 0 30,833 2015 Denison Mines Corp. 72 0 42,243 TOTAL 641 84 302,127

PHOENIX DEPOSIT EXPLORATION DRILLING During the summer of 2008, WR-249 was drilled on geophysics line 4300 to test resistivity

target “A”. WR-249 was spotted 90 m northwest of WR-190A, which had been lost in the

sandstone 34 m above the unconformity in 2003. The hole encountered strong

desilicification, silicification, hydrothermal hematite, druzy quartz and increased fracture

density, with progressively more intense alteration towards the unconformity, together with a

strong grey bleached zone consisting of extremely fine grained pyrite which provided a

strong visual contrast to bleached zones in other nearby holes. At the unconformity,

disseminated and massive uranium mineralization was present from 406.65 m to 409 m. The

assay grade was 1.06% U3O8 over 2.35 m. This was the highest grade intercept on the

Property to date. This hole was located seven kilometres northeast of the previous work in

the WR-204 area and, more significantly, was drilled on the hanging wall rather than the

footwall side of the quartzite ridge.

Target “B” was tested by WR-251, which was located 600 m along strike from WR-249. It

intersected similar alteration along with three mineralized zones occurring both at the

unconformity and in the basement. The best intersection graded 0.78% U3O8 over 2.25 m.

All 2008 follow-up drilling was located in the WR-251 area. Additional uranium mineralization

(1.4% U3O8 over 4.0 m and 1.75% U3O8 over 0.5 m) was intersected in WR-253, which was

drilled to test for mineralization 15 m to the southeast of WR-251.

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All drill holes completed during the summer of 2008 intersected either uranium mineralization

or very strong alteration located in the hanging wall to the quartzite unit. This new discovery

was termed Phoenix.

During 2009, three drill programs consisting of a total of 43 diamond drill holes (19,006 m),

were carried out, each of which established significant milestones in the advancement of the

Property. During the winter program, the first indications of higher grade mineralization came

from hole WR-258, which returned 11.8% U3O8 over 5.5 m from a depth of 397 m. The

summer drill program continued to test the Phoenix discovery, with hole WR-273 returning a

value of 62.6% U3O8 over 6.0 m at a depth of 405 m. Mineralization was monomineralic

pitchblende with very low concentrations of accessory minerals and was reported to be

remarkably similar to the high-grade McArthur River P2 deposits. Most of the mineralization

occurs as a horizontal sheet at the base of the Athabasca sandstone proximal to where a

graphitic pelite unit in the basement intersects the unconformity. In addition, the alteration

changes to the northeast with intense and strong basement bleaching becoming more

prominent, and the strongest graphitic faulting observed. More significantly, the new

mineralized zone returned the highest grades intersected in more than 40 years of

continuous exploration on the Property.

A further drill program in the fall of 2009 established continuity of the high-grade portion of

the mineralized zone and extended the overall zone as a possibly continuous unit for a strike

length of greater than one kilometre.

During 2010, 62 diamond drill holes totalling 28,362.3 m were carried out on two claims

along the Phoenix deposit trend. Of the 62 drill holes, 59 totalling 27,853.25 m were

completed to the desired depth and three were lost or abandoned due to poor ground

conditions or excessive deviation. The three lost holes were re-drilled and successfully

completed to the desired depth. Twenty-seven holes were drilled on claim S-98341 during

two drill seasons from January to April and June to August. Thirty-five holes were drilled on

claim S-97909 during two drill seasons from January to April and June to August. The two-

phase drilling program was carried out during the periods of January to April 2010 and June

to August 2010.

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During 2011, a two-phase drilling program of 80 diamond drill holes totalling 38,426.6 m was

carried out on mineral dispositions S-97908, S-97909, and S-98341. Of the 80 drill holes

completed, 77 were successfully completed to design depth.

During 2012, Denison completed 51 diamond drill holes totalling 23,073 m on the Phoenix

deposit during two drilling campaigns.

In 2013, 30 diamond drill holes totaling 13,797 m were carried out on mineral dispositions

across the Property of which 14 were completed as infill delineation drilling on Phoenix zone

A.

In 2014, an additional 11 diamond drill holes were completed on Phoenix zone A to extend

higher grade portions of the deposit.

Since 2008, 263 drill holes totalling 123,749 m of drilling have delineated the Phoenix deposit

(Figure 10-1, Table 10-2). Well-established drilling industry practices were used in the

drilling programs.

TABLE 10-2 PHOENIX DRILLING STATISTICS Denison Mines Corp. – Wheeler River Property

Deposit Year Company # Holes Total Drilled (m) Phoenix 2008 Denison 14 6,499

2009 Denison 31 14,549 2010 Denison 55 25,949 2011 Denison 71 34,436 2012 Denison 51 23,073 2013 Denison 25 12,083 2014 Denison 10 4,298 2015 Denison 6 2,862

Phoenix Total 263 123,749

Target # Holes Total Drilled (m) Zone A 137 62,678 Zone B 55 25,347 Zone C 24 10,438 Zone D 27 15,214 North Target 18 9,482 East Target 2 591

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To date, the Phoenix deposit area has been systematically drill tested over approximately

one kilometre of strike length at a nominal 25 m to 50 m section spacing (Figure 10-1).

Delineation diamond drilling at Phoenix was primarily done with NQ sized core (47.6 mm

diameter) in holes WR-249 through WR-275 and HQ sized core (63.5 mm diameter) reducing

down to NQ at 350 m in holes WR-276 through WR-561A, with most holes successfully

penetrating into the basement. In general, drilling in the higher grade areas of the Phoenix

deposit has been conducted on a nominal drill hole grid spacing of 25 m northeast-southwest

by 10 m northwest-southeast. Some additional infill holes were drilled primarily to test the

spatial continuity of the mineralization. The most notable results from drilling to date are the

intersections of 6.0 m of 62.6% U3O8 in hole WR-273, 3.5 m of 58.2% U3O8 in hole WR-305,

8.4 m of 38.4% U3O8 in hole WR-401, and 10.5 m of 50.1% U3O8 in hole WR-525. The bulk

of the flat lying high-grade mineralization is positioned at and sub-parallel to the

unconformity.

All holes were logged for lithology, structure, alteration, mineralization, and geotechnical

characteristics. Data were entered into DHLogger software on laptops in the field. The

DHLogger data were transferred into a Fusion database. All drill hole data were validated

throughout the drilling program and as an integral component of the current recent resource

estimation work. Hard copies of drill logs are stored at site.

ZONE A

ZONE B1

ZONE B2

Quartzite

Garnetiferous Pelite

Graphitic Pelite

Pelite

Semipelite

WS Thrust Fault w /cross structure

Phoenix Deposit

N

0 50

Metres

100 150 200

UTM Projection WGS 84-13NNovember 2015


Phoenix DepositDrill Hole Location Map

Denison Mines Corp.


Figure 10-1

16

0-

ww

w.rp

acan

.co

m

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GRYPHON DEPOSIT EXPLORATION DRILLING The first exploration drilling in the Gryphon area began in 1988 and continued intermittently

through 2013.

In 2013, Denison drilled two holes, WR-507D1 and WR-509. WR-507D1 was drilled

approximately 40 m up dip on section northwest of hole ZK-23, to test for more favourable

geology (Figure 10-2). No significant mineralization was intersected at the unconformity or in

the basement, but similar lithological units and structure were intersected which hosted

mineralization in the ZK-02/ZK-04/ZK-06 drill fence. WR-509 was drilled approximately 100

m grid west of the ZK-02/ZK-04/ZK-06 drill fence within the K1a conductive corridor to test for

unconformity mineralization. No significant unconformity alteration or mineralization was

intersected, however, there was some weak basement mineralization intersected over

approximately 0.5 m from 634.2 m within a pelitic lens in a large pegmatite body. No further

follow-up was recommended for either hole at this time.

In 2014, Denison completed a drilling campaign of 25 holes for 18,546 m which included the

Gryphon discovery hole WR-556. WR-556 was drilled on the ZK-02/ZK-04/ZK-06 fence to

test two targets:

1. The unconformity down-dip of a sandstone structure intersected in ZK-06, and

2. The down-dip projection of basement hosted mineralization intersected in ZK-04 and ZK-06.

No unconformity mineralization was intersected, but high grade mineralization was

intersected at the contact of a graphitic pelite and a quartzite unit down dip from hole ZK-06.

The mineralization graded 15.3% U3O8 over 4.0 m from 697.5 m (approximately 207 m below

the unconformity). This mineralization was termed the Upper Lens.

Legend:

Pelites

Quartzite

Pegmatite

Drill Hole Collar

Property BoundaryGraphitic Pelite

Granite

N

November 2015 Source: Denison Mines Corp., 2015.


Gryphon Deposit2013 Drill Hole Location Map

Denison Mines Corp.


Figure 10-2

10-8

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In 2014, Denison also drilled holes WR-558 and WR-560. WR-558 was drilled to target the

contact of the unconformity with the western most graphitic unit northwest of ZK-02. While

no unconformity mineralization was encountered, basement mineralization was intersected in

a pegmatite unit approximately 54 m below the unconformity. The mineralization graded

7.3% U3O8 over 0.5 m from 611.7 m and is considered peripheral mineralization to the

Gryphon Upper Lens. WR-560 was drilled 35 m up dip of the WR-556 intersection. WR-560

intersected high grade mineralization at a lower stratigraphic position to that found in WR-

556 and was termed the Lower Lens. The WR-560 mineralization graded 21.2% U3O8 over

4.5 m from 759 m (approximately 234 m below the unconformity).

Since the discovery of Gryphon, definition drilling has continued on both the Upper Lens and

Lower Lens. The Upper Lens has been defined as a body of multiple stacked high grade

lenses that plunge toward the northeast, approximately 80 m to 370 m below the sub-

Athabasca unconformity. Denison followed up the 2014 drilling with 2015 winter and

summer drilling campaigns with an additional 37 holes, totalling 21,591 m. As of September

17, 2015, the effective date of the current Mineral Resource estimate, Denison and

predecessor companies have drilled a total of 69 holes totalling 44,083 m over the Gryphon

deposit. Table 10-3 lists the holes by drilling program.

TABLE 10-3 GRYPHON DRILLING STATISTICS Denison Mines Corp. – Wheeler River Property

Deposit Year Company # Holes Total Drilled (m) Gryphon 1988 SMDC 3 1,848

2001 Cameco 1 584 2013 Denison 3 1,515 2014 Denison 25 18,546 2015 Denison 37 21,591

Gryphon Total 69 44,083

Diamond drilling at Gryphon was primarily done with NQ sized core (47.6 mm diameter) with

68 of 76 holes angled between 67° to 79° to the northwest with the remaining holes drilled

vertically.

Highlights from the Gryphon drilling program are listed in Table 10-4.

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TABLE 10-4 GRYPHON DEPOSIT MINERAL INTERSECTIONS Denison Mines Corp. – Wheeler River Property

Hole no. From (m) To (m) Thick (m) % U3O8 GT WR-560 759.0 763.5 4.5 21.21 95.46 WR-556 697.5 701.5 4.0 15.33 61.33

WR-573D1 548.5 551.0 2.5 22.16 55.39 WR-569A 680.0 683.5 3.5 13.16 46.07 WR-604 779.0 784.5 5.5 6.34 34.86

WR-584B 641.6 646.1 4.5 7.50 33.75 WR-569A 702.5 705.5 3.0 10.27 30.82 WR-574 696.5 698.5 2.0 14.60 29.19 WR-571 757.5 760.0 2.5 8.79 21.98

WR-571D2 512.0 517.5 5.5 3.95 21.72 Notes:

1. Intersection interval is composited at cut-off grade of 1.0% U3O8 and minimum thickness of 1 m.

DRILL HOLE SURVEYING The collar locations of drill holes are spotted on a grid established in the field, and collar sites

are surveyed by differential base station GPS using the NAD83 UTM zone 13N reference

datum. The drill holes have a concise naming convention with the prefix “WR” denoting

“Wheeler River”” followed by the number of the drill hole. In general, most of the drilling was

completed on northwest-southeast oriented profiles spaced approximately 50 m apart.

The trajectory of all drill holes is determined with a Reflex instrument in single point mode,

which measures the dip and azimuth at 50 m intervals down the hole with an initial test taken

six metres below the casing and a final measurement at the bottom of the hole. All

mineralized and non-mineralized holes within the Phoenix deposit are cemented from

approximately 25 m below the mineralized zone to approximately 25 m above the zone. All

mineralized and non-mineralized holes within the Gryphon deposit are cemented for the

entire basement column to approximately 25 m above the unconformity.

RADIOMETRIC LOGGING OF DRILL HOLES All drill holes on the Property are logged with a radiometric probe to measure the natural

gamma radiation, from which an indirect estimate of uranium content can be made. Most of

the U3O8 grade data (76%) used for the Phoenix Mineral Resource estimate are obtained

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from chemical assays of the rock. The remainder of the data are derived from radiometric

probe results, typically when poor drill core recovery prevents representative sampling for

chemical assays. For the Gryphon Mineral Resource estimate, 100% of the U3O8 grade data

are obtained from chemical assay of the rock.

RADIOMETRIC PROBING Probing with a Mount Sopris gamma logging unit employing a triple gamma probe (2GHF-

1000) was completed systematically on every drill hole. The probe measures natural gamma

radiation using three different detectors: one 0.5 in. by 1.5 in. sodium iodide (NaI) crystal

assembly and two Geiger Mueller (G-M) tubes installed above the NaI detector. These G-M

tubes have been used successfully to determine grade in very high concentrations of U3O8.

By utilizing three different detector sensitivities (the sensitivity of the detectors is very

different from one detector to another), these probes can be used in both exploration and

development projects across a wide spectrum of uranium grades. Accurate concentrations

can be measured in uranium grades ranging from less than 0.1% to as high as 80% U3O8.

Data are logged from all three detectors at a speed of 10 m/min down hole and 15 m/min up

hole through the drill rods.

The radiometric or gamma probe measures gamma radiation which is emitted during the

natural radioactive decay of uranium (U) and variations in the natural radioactivity originating

from changes in concentrations of the trace element thorium (Th) as well as changes in

concentration of the major rock forming element potassium (K).

Potassium decays into two stable isotopes (argon and calcium) which are no longer

radioactive, and emits gamma rays with energies of 1.46 MeV. Uranium and thorium,

however, decay into daughter products which are unstable (i.e., radioactive). The decay of

uranium forms a series of about a dozen radioactive elements in nature which finally decay

to a stable isotope of lead. The decay of thorium forms a similar series of radioelements. As

each radioelement in the series decays, it is accompanied by emissions of alpha or beta

particles or gamma rays. The gamma rays have specific energies associated with the

decaying radionuclide. The most prominent of the gamma rays in the uranium series

originate from decay of 214Bi (bismuth 214), and in the thorium series from decay of 208Tl

(thallium 208).

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The natural gamma measurement is made when a detector emits a pulse of light when

struck by a gamma ray. This pulse of light is amplified by a photomultiplier tube, which

outputs a current pulse which is accumulated and reported as “counts per second”, or “cps”.

The gamma probe is lowered to the bottom of a drill hole and data are recorded as the tool

travels to the bottom and then is pulled back up to the surface. The current pulse is carried

up a conductive cable and processed by a logging system computer which stores the raw

gamma cps data.

Since the concentrations of these naturally occurring radioelements vary between different

rock types, natural gamma ray logging provides an important tool for lithologic mapping and

stratigraphic correlation. For example, in sedimentary rocks, sandstones can be easily

distinguished from shales due to the low potassium content of the sandstones compared to

the shales. The greatest value of the gamma ray log in uranium exploration, however, is in

determining equivalent uranium grade.

The basis of the indirect uranium grade calculation (referred to as "eU3O8" for "equivalent

U3O8") is the sensitivity of the detector used in the probe which is the ratio of cps to known

uranium grade and is referred to as the probe calibration factor. Each detector’s sensitivity is

measured when it is first manufactured and is also periodically checked throughout the

operating life of each probe against a known set of standard "test pits," with various known

grades of uranium mineralization or through empirical calculations. Application of the

calibration factor, along with other probe correction factors, allows for immediate grade

estimation in the field as each drill hole is logged.

Downhole total gamma data are subjected to a complex set of mathematical equations,

taking into account the specific parameters of the probe used, speed of logging, size of bore

hole, drilling fluids, and presence or absence of any type of drill hole casing. The result is an

indirect measurement of uranium content within the sphere of measurement of the gamma

detector. A Denison in-house computer program known as GAMLOG converts the

measured counts per second of the gamma rays into 10 cm increments of equivalent percent

U3O8 (%eU3O8). GAMLOG is based on the Scott’s Algorithm developed by James Scott of

the Atomic Energy Commission (AEC) in 1962 and is widely used in the industry.

The conversion coefficients for conversion of probe counts per second to %eU3O8 equivalent

uranium grades are based on the calibration results obtained at the Saskatchewan Research

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Council (SRC) uranium calibration pits (sodium iodide crystal) and empirical values

developed in-house (Sweet and Petrie 2010) for the triple-gamma probe (Figure 10-3).

SRC downhole probe calibration facilities are located in Saskatoon, Saskatchewan. The

calibration facilities test pits consist of four variably mineralized holes, each approximately

four metres thick. The gamma probes are calibrated a minimum of two times per year,

usually before and after both the winter and summer field seasons.

Drilling procedures, including collar surveying, downhole Reflex surveying, and radiometric

probing are standard industry practice.

FIGURE 10-3 CALIBRATION CURVE FOR GEIGER-MUELLER SN 3818 PROBE

SAMPLING METHOD AND APPROACH

DRILL CORE HANDLING AND LOGGING PROCEDURES At each drill site, core is removed from the core tube by the drill contractors and placed

directly into three row NQ wooden core boxes with standard 1.5 m length (4.5 m total) or two

row HQ wooden boxes with standard 1.5 m (3.0 m total). Individual drill runs are identified

55 227105066140142610

1,6102,225

2,5002,710

2,800

3,1903,430

3,327

2,375

3,481

65140

1,590

564153

2,738 2,9752,214

3,160

3,475

3,475

3,450

2,700

3,741

2,832

1,659

3,535

2,865

0.0

20.0

40.0

60.0

80.0

100.0

0 1000 2000 3000 4000 5000

Gra

de %

eU

3O8

Total Counts

Synthetic Total Count from SN3688-3818-GM-12 K-factor (%U3O8) = 60*e-5; Dead Time = 200 microseconds

with Sampled Assay Results to February 2012vs Grade% U3O8

SN3818 Assay

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with small wooden blocks, onto which the depth in metres is recorded. Diamond drill core is

transported at the end of each drill shift to an enclosed core handling facility at Denison’s

Wheeler River camp. The core handling procedures at the drill site are industry standard.

Drill holes are logged at the Wheeler River camp core logging facilities by Denison

personnel.

Before the core is split for assay, the core is photographed, descriptively logged, measured

for structures, surveyed with a scintillometer, and marked for sampling. Sampling of the

holes for assay is guided by the observed geology, radiometric logs, and readings from a

hand-held scintillometer.

The general concept behind the scintillometer is similar to the gamma probe except the

radiometric pulses are displayed on a scale on the instrument and the respective count rates

are recorded manually by the technician logging the core or chips. The hand-held

scintillometer provides quantitative data only and cannot be used to calculate uranium

grades; however, it does allow the geologist to identify uranium mineralization in the core and

to select intervals for geochemical sampling, as described below.

Scintillometer readings are taken throughout the hole as part of the logging process, usually

over three metre intervals, and are averaged for the interval. In mineralized zones, where

scintillometer readings are above five times background (approximately 500 cps depending

on the scintillometer being used), readings are recorded over 10 cm intervals and tied to the

run interval blocks. The scintillometer profile is then plotted on strip logs to compare and

adjust the depth of the downhole gamma logs. Core trays are marked with aluminum tags as

well as felt marker.

DRILL CORE SAMPLING ASSAY SAMPLING Denison submits assay samples for geochemical analysis for all the cored sections through

mineralized intervals, where core recovery permits. All mineralized core is measured with

the scintillometer described above by removing each piece of drill core from the ambient

background, noting the most pertinent reproducible result in counts per second, and carefully

returning it to its correct place in the core box. Any core registering over 500 cps is flagged

for splitting and sent to the laboratory for assay. Early drill holes were sampled using

variable intervals (0.2 m to 1.0 m); after drill hole WR-253, holes were sampled using 0.5 m

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lengths. Barren samples are taken to flank both ends of mineralized intersections, with flank

sample lengths at least 0.5 m on either end, which, however, may be significantly more in

areas with strong mineralization.

All core samples are split with a hand splitter according to the sample intervals marked on

the core. One-half of the core is returned to the core box for future reference and the other

half is bagged, tagged, and sealed in a plastic bag. Bags of mineralized samples are sealed

for shipping in metal or plastic pails depending on the radioactivity level. Samples collected

on 0.5 m spacing through the mineralized zone are analyzed using inductively coupled

plasma optical emission spectroscopy (ICP-OES) (Section 11).

OTHER SAMPLING Three other types of drill core samples are collected as follows:

1) Composite geochemical samples are collected over approximately 10 m intervals inthe upper Athabasca sandstone and in fresh lithologies beneath the unconformity(basement) and over five metre intervals in the basal sandstone and alteredbasement units. The samples consist of one to two centimetre disks of core collectedat the top or bottom of each row of core in the box over the specified interval. Care istaken not to cross lithological contacts or stratigraphic boundaries.

2) Representative/systematic core disks (one to five centimetres in width) are collectedat regular five to ten metre intervals throughout the entire length of core untilbasement lithologies become unaltered. These samples are analyzed for clayminerals using reflectance spectroscopy.

3) Select “spot” samples are collected from significant geological features (i.e.,radiometric anomalies, structure, alteration etc). Core disks one to two centimetrethick are collected for reflectance spectroscopy and split core samples, over thedesired interval, are sent for geochemical analysis. Ten centimetre wide coresamples may also be collected for density measurement.

These sampling types and approaches are typical of uranium exploration and definition

drilling programs in the Athabasca Basin. The drill core handling and sampling protocols are

industry standard.

CORE RECOVERY AND USE OF PROBE DATA At Phoenix, the mineralized zones (sandstones or basement) are moderately to strongly

altered, and occasionally disrupted by fault breccias. In places, the core can be broken and

blocky, however, recovery is generally good with an overall average of 89.65%. Local

intervals of up to five metres with less than 80% recovery have been encountered due to

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washouts during the drilling process. Where 80% or less of a composited interval is

recovered during drilling (>20% core loss), or where no geochemical sampling has occurred

across a mineralized interval, uranium grade determination has been supplemented by

radiometric probe data. Radiometric probe data accounts for approximately 23% of the drill

holes used for the Mineral Resource estimate at Phoenix. There are 1,708 U3O8 assay

records totalling 848 m in the Phoenix deposit database. Of these, 1,464 U3O8 assay

records totalling 726 m are in zone A and 244 U3O8 assay records totalling 122 m are in zone

B.

Core recovery at Gryphon is excellent. Of the 69 drill holes drilled at Gryphon, 19 drill holes

contained only radiometric data and were not sampled for assay, 36 drill holes contained

both radiometric and assays, and 14 drill holes did not have any grade data. In total there

were 55 drill holes used to interpret the mineralized domains, but only the 36 holes

containing assays were used for Mineral Resource estimate. There are 1,019 U3O8 assay

records totalling 510 m in the Gryphon deposit database

RPA is not aware of any drilling, sampling, or recovery factors that could materially impact

the accuracy and reliability of the results.

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11 SAMPLE PREPARATION, ANALYSES AND SECURITY As described in Section 10 Drilling, core from the Property is photographed, logged, marked

for sampling, split, bagged, and sealed for shipment by Denison personnel at the Wheeler

River field logging facility. All samples for assay or geochemical analyses are sent to the

Saskatchewan Research Council Geoanalytical Laboratories (SRC) in Saskatoon,

Saskatchewan. Samples for reflectance clay analyses have been analyzed using a PIMA

spectrometer or an ArcSpectro FT-NIR ROCKET spectrometer and sent to Rekasa Rocks

Inc. (Rekasa) or AusSpec International Ltd. (AusSpec), respectively, for interpretation. All

samples for geochemical or clay analyses are shipped to Saskatoon by airfreight or ground

transport. All samples for U3O8 assays are transported by land to the SRC laboratory by

Denison personnel. A sample transmittal form is prepared that identifies each batch of

samples. SRC performs sample preparation on all samples submitted. There is no sample

preparation, apart from drying, involved for the samples sent for clay analyses.

GEOCHEMICAL SAMPLE PREPARATION PROCEDURES

SAMPLE RECEIVING Samples are received at the SRC laboratory as either dangerous goods (qualified Transport

of Dangerous Goods (TDG) personnel required) or as exclusive use only samples (no

radioactivity documentation attached). On arrival, samples are assigned an SRC group

number and are entered into the Laboratory Information Management System (LIMS).

All received sample information is verified by sample receiving personnel: sample numbers,

number of pails, sample type/matrix, condition of samples, request for analysis, etc. The

samples are then sorted by radioactivity level. A sample receipt and sample list is then

generated and e-mailed to the appropriate authorized personnel at Denison. Denison is

notified if there are any discrepancies between the paperwork and samples received.

SAMPLE SORTING To ensure that there is no cross contamination between sandstone and basement, non-

mineralized, low level, and high-level mineralized samples, they are sorted by their matrix

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and radioactivity level. Samples are firstly sorted in their group into matrix type (sandstone

and basement/mineralized).

The samples are then checked for their radioactivity levels. Using a Radioactivity Detector

System, the samples are classified into one of the following levels:

• “Red Line” (minimal radioactivity) <500 cps

• “1 Dot” 500 – 1,999 cps

• “2 Dots” 2000 – 2,999 cps

• “3 Dots” 3000 – 3,999 cps

• “4 Dots” 4000 – 4,999 cps

• “UR” (unreadable) >5,000 cps

The samples are then sorted into ascending sample numerical order and transferred to their

matrix designated drying oven.

SAMPLE PREPARATION After the drying process is complete, “Red line” and “1 Dot” samples are sent for further

processing (crushing and grinding) in the main SRC laboratory. All radioactive samples at “2

Dots” or higher are sent to a secure radioactive facility at SRC for the same sample

preparation. Plastic snap top vials are labelled according to sample numbers and sent with

the samples to the appropriate crushing room. All highly radioactive materials are kept in a

radioactive bunker until they can be transported by TDG trained individuals to the

radioactivity facility for processing.

Rock samples are jaw crushed to 60% passing -2 mm. Samples are placed into the crusher

(one at a time) and the crushed material is put through a splitter. The operator ensures that

the distribution of the material is even, so there is no bias in the sampling. One portion of the

material is placed into the plastic snap top vial and the other is put in the sample bag (reject).

The first sample from each group is checked for crushing efficiency by screening the vial of

rock through a 2 mm screen. A calculation is then carried out to ensure that 60% of the

material is -2 mm. If the quality control (QC) check fails, the crushing is redone and checked

for crushing efficiency; if it still fails, the QC department is notified and corrective action is

taken.

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The crusher, crusher catch pan, splitter, and splitter catch pan are cleaned between each

sample using compressed air.

The reject material is returned to its original sample bag and archived in a plastic pail with the

appropriate group number marked on the outside of the pail. The vials of material are then

sent to grinding; each vial of material is placed in pots (six pots per grind) and ground for two

minutes. The material is then returned to the vials. The operator shakes the vial to check

the fineness of the material by looking for visible grains and listening for rattling. The sample

is then screened through a 106 µm sieve, using water. The sample is then dried and

weighed; to pass the grinding efficiency QC, there must be over 90% of the material at -106

µm. The material is then transferred to a labelled plastic snap top vial.

The pots are cleaned out with silica sand and blown out with compressed air at the start of

each group. In the radioactive facility, the pots are cleaned with water. Once sample pulps

are generated, they are returned to the main laboratory to be chemically processed prior to

analysis. All containers are identified with sample information and their radioactivity status at

all times. When the preparation is completed, the radioactive pulps are returned to a secure

radioactive bunker, until they can be transported back to the radioactive facility. All rejected

sample material not involved in the grinding process is returned to the original sample

container. All highly radioactive materials are stored in secure radioactive designated areas.

Sample preparation methods for the samples used in the Gryphon and Phoenix Mineral

Resource estimates meet or exceed industry standards.

ANALYTICAL METHODS All assay core samples from Gryphon and Phoenix were analyzed by the ICP1 package

offered by SRC. Composite geochemical samples, up to and including WR-269, were also

analyzed using this method after which the method was changed to ICP-MS1 because of a

lower detection limit.

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METHOD: ICP1-URANIUM MULTI-ELEMENT EXPLORATION ANALYSIS BY ICP-OES Method Summary: In ICP-OES analysis, the atomized sample material is ionized and the

ions then emit light (photons) of a characteristic wavelength for each element, which is

recorded by optical spectrometers. Calibrations against standard materials allow this

technique to provide a quantitative geochemical analysis.

The analytical package includes 62 analytes (46 total digestion, 16 partial digestion), with

nine analytes being analyzed for both partial and total digestions (Ag, Co, Cu, Mo, Ni, Pb, U,

V, and Zn) plus boron. These samples are also sometimes analyzed for Au by fire assay.

Partial Digestion: For partial digestion analysis, samples were crushed to 60% -2 mm and

a 100 g to 200 g sub-sample was split out using a riffler. The sub-sample pulverized to 90%

-106 µm using a standard puck and ring grinding mill. The sample was then transferred to a

plastic snap top vial. An aliquot of pulp is digested in a digestion tube in a mixture of

HNO3:HCl, in a hot water bath for approximately one hour, then diluted to 15 mL using de-

ionized water. The samples were then analyzed using a Perkin Elmer ICP-OES instrument

(models DV4300 or DV5300)

Total Digestion: An aliquot of pulp is digested to dryness in a hot block digestor system

using a mixture of concentrated HF:HNO3:HClO4. The residue is dissolved in 15 mL of dilute

HNO3 and analyzed using the same instrument(s) as above.

METHOD: ICPMS1 - THE MULTI-ELEMENT DETERMINATION BY ICP-MS Method Summary: The analytical package includes the analysis of 47 elements and oxides

using a three acid (HF/HNO3/HClO4) “total” digestion and a suite of 42 elements using a two

acid (HNO3/HCl) “partial” digestion. Analysis of the lead isotopes (204Pb, 206Pb, 207Pb, and 208Pb) are also included in the package. Boron is determined by ICP-OES analysis after

fusion with NaO2/NaCO3. PerkinElmer instruments (models Optima 300DV, Optima 4300DV,

and Optima 5300DV) are currently in use. The samples generally analyzed by this package

are non-radioactive, non-mineralized sandstones and basement rocks with low

concentrations of uranium (<100 ppm).

Partial Digestion: An aliquot of pulp is digested in a mixture of ultra-pure concentrated nitric

and hydrochloric acids (HNO3:HCl) in a digestion tube in a hot water bath then diluted to 15

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mL using de-ionized water prior to analysis. As, Ge, Hg, Sb, Se and Te are subject to partial

digestion only, as these elements are not suited to total digestion analysis. The ICP-MS

instruments used are PerkinElmer Elan DRC II.

Total Digestion: An aliquot of pulp is digested to dryness in a hot block digestor system

using a mixture of ultra-pure concentrated acids HF:HNO3:HClO4. The residue is dissolved in

15 mL of 5% HNO3 and made to volume using de-ionized water prior to analysis.

METHOD: U3O8 WT% ASSAY - THE DETERMINATION OF U3O8 WT% IN SOLID SAMPLES BY ICP-OES Method Summary: When ICP1 U partial values are ≥1,000 ppm, sample pulps are re-

assayed for U3O8 using SRC's ISO/IEC 17025:2005-accredited U3O8 (wt%) method. In the

case of uranium assay by ICP-OES, a pulp is already generated from the first phase of

preparation and assaying (discussed above).

Aqua Regia Digestion: An aliquot of sample pulp is digested in a 100 mL volumetric flask in

a mixture of 3:1 HCl:HNO3, on a hot plate for approximately one hour, then diluted to volume

using de-ionized water. Samples are diluted prior to analysis by ICP-OES.

Instrument Analysis: Instruments in the analysis are calibrated using certified commercial

solutions. The instruments used were PerkinElmer Optima 300DV, Optima 4300DV, or

Optima 5300DV.

Detection Limits: 0.001% U3O8

METHOD: U3O8 WT% ASSAY - THE DETERMINATION OF U3O8 WT% IN SOLID SAMPLES BY DELAYED NEUTRON COUNTING SRC in 2009 documented the method summary for the Delayed Neutron Counting (DNC)

technique as follows. Samples previously prepared as pulps for ICP total digestion are used

for the DNC analysis. The pulps are irradiated in a Slowpoke 2 nuclear reactor for a given

period of time. After irradiation, the samples are pneumatically transferred to a counting

system equipped with six helium-3 detectors. After a suitable delay period, neutrons

emanating from the sample are counted. The proportion of delayed neutrons emitted is

related to the uranium concentration. For low concentrations of uranium, a minimum of one

gram of sample is preferred, and larger sample sizes (two to five grams) will improve

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precision. Several blanks and certified uranium standards are analyzed to establish the

instrument calibration. In addition, control samples are analyzed with each batch of samples

to monitor the stability of the calibration. At least one in every ten samples is analyzed in

duplicate. The results of the instrument calibration, blanks, control samples, and duplicates

must be within specified limits otherwise corrective action is required.

Analysis for uranium by DNC incorporates four separate flux/site conditions of varying

sensitivity to produce an effective range of analysis from zero to 150,000 µg U per capsule

(samples of up to 90% U can be analyzed by weighing a fraction of a gram to ensure that

there is no more than 150,000 µg U in the capsule). Each condition is calibrated using

between three and seven reference materials. For each condition, one of these materials is

designated as a calibration check sample. As well, there is an independent control sample

for each condition.

DRILL CORE BULK DENSITY ANALYSIS Drill core samples collected for bulk density measurements were sent to SRC. Samples

were first weighed as received and then submerged in de-ionized water and re-weighed.

The samples were then dried until a constant weight was obtained. The sample was then

coated with an impermeable layer of wax and weighed again while submersed in de-ionized

water. Weights were entered into a database and the bulk density of each sample was

calculated. Water temperature at the time of weighing was also recorded and used in the

bulk density calculation.

REFLECTANCE CLAY ANALYSES Prior to 2015, core chip samples for clay analysis were analyzed using a PIMA II

spectrometer. This included all analyses performed on samples from the Phoenix deposit.

Short wave infrared (SWIR) spectra were sent to Rekasa, a private facility in Saskatoon, for

interpretation. Samples were air or oven dried prior to analysis in order to remove any

excess moisture. Reflective spectra for the various clay minerals present in the sample were

compared to the spectral results from Athabasca samples for which the clay mineral

proportions have been determined in order to obtain a semi-quantitative clay estimate for

each sample.

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In 2015, core chip samples for clay reflectance analysis were analyzed using an ArcSpectro

FT-NIR (Fourier transform near-infrared) ROCKET spectrometer. This included all analyses

performed on samples from the Gryphon deposit. Sample collection and preparation is

identical to procedures used for PIMA analysis. The transmission spectra of the reflectance

samples were sent to AusSpec, based in New Zealand. The spectra are analyzed using an

aiSIRIS automated spectral interpretation system. The mineral assemblage for each sample

is listed in order of spectral dominance and represents the spectral contribution of the

mineral to the spectrum. The results compared well with previous PIMA spectra

interpretations undertaken by Rekasa.

QUALITY ASSURANCE AND QUALITY CONTROL Quality assurance/quality control (QA/QC) programs provide confidence in the geochemical

results and help ensure that the database is reliable to estimate Mineral Resources. Denison

has developed and documented several QA/QC procedures and protocols for all exploration

projects which include the following components:

1) Determination of precision – achieved by regular insertion of duplicates for eachstage of the process where a sample is taken or split;

2) Determination of accuracy – achieved by regular insertion of standards ormaterials of known composition;

3) Checks for contamination – achieved by insertion of blanks.

RPA reviewed Denison’s procedures and protocols and considers them to be reasonable

and acceptable.

SAMPLE STANDARDS, BLANKS AND FIELD DUPLICATES URANIUM ASSAY STANDARDS Analytical standards are used to monitor analytical precision and accuracy, and field

standards are used as an independent monitor of laboratory performance. Six uranium

assay standards have been prepared for use in monitoring the accuracy of uranium assays

received from the laboratory. Due to the radioactive nature of the standard material,

insertion of the standard materials is preferable at SRC instead of in the field. During sample

processing, the appropriate standard grade is determined, and an aliquot of the appropriate

standard is inserted into the analytical stream for each batch of materials assayed.

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Denison uses standards provided by its Wheeler River Joint Venture partner Cameco for

uranium assays. Cameco standards are added to the sample groups by SRC personnel,

using the standards appropriate for each group. As well, for each assay group, an aliquot of

Cameco’s blank material is also included in the sample run. In a run of forty samples, at

least one will consist of a Cameco standard and one will consist of a Cameco blank.

Accuracy of the analyses and values obtained relative to the standard values, based on the

analytical results of the six reference standards used, is acceptable for Mineral Resource

estimates. Chronological plots for the six standards are shown in Figures 11-1 to 11-6 with

upper limit (UL) and lower limit (LL) being equal to the mean plus or minus three standard

deviations respectively. Note in Figures 11-1 and 11-6 that the standards were changed

during 2011.

FIGURE 11-1 USTD1 ANALYSES

0.25

0.255

0.26

0.265

0.27

0.275

0.28

0.285

31/0

7/20

0901

/11/

2010

13/0

1/20

1005

/06/

2010

19/0

7/20

1019

/08/

2010

09/0

3/20

1009

/09/

2010

09/0

9/20

1021

/10/

2010

21/0

4/20

1124

/08/

2011

10/0

7/20

1116

/11/

2011

12/0

7/20

1119

/04/

2012

22/0

5/20

1208

/03/

2012

28/0

3/20

1328

/08/

2013

25/0

3/20

1415

/04/

2014

16/0

5/20

1406

/11/

2014

27/0

8/20

1421

/11/

2014

25/0

5/20

1519

/08/

2015

24/0

9/20

15

Stan

dard

Val

ue %

U (p

pm)

Analysis Date

Standard Contol Chart2011_USTD1 - U3O8 per AR_ICP

Module: STD Project WR

USTD1 Average USTD1_STD_UL USTD1_STD_LL USTD1 Assay

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0.780.8

0.820.840.860.88

0.90.920.94

28/0

7/20

0925

/11/

2009

14/0

1/20

1005

/06/

2010

09/0

9/20

1013

/10/

2010

14/0

4/20

1117

/08/

2011

10/0

7/20

1116

/11/

2011

17/1

1/20

1104

/05/

2012

22/0

5/20

1208

/03/

2012

26/0

4/20

1328

/08/

2013

25/0

3/20

1415

/04/

2014

30/0

5/20

1409

/02/

2014

21/1

1/20

1425

/05/

2015

27/0

8/20

1524

/09/

2015

Stan

dard

Val

ue %

U (p

pm)

Analysis Date




2.752.8

2.852.9

2.953

3.053.1

3.153.2

3.25

07/0

7/20

09

31/0

7/20

09

14/0

1/20

10

30/0

4/20

10

05/0

6/20

10

19/0

8/20

10

09/0

3/20

10

21/1

0/20

10

11/0

3/20

10

05/0

2/20

11

24/0

8/20

11

10/0

7/20

11

16/1

1/20

11

24/1

1/20

11

23/0

3/20

12

04/0

5/20

12

27/0

4/20

12

16/0

8/20

12

09/0

7/20

12

30/0

5/20

14

27/0

8/20

14

21/1

1/20

14

Stan

dard

Val

ue %

U (p

pm)

Analysis Date




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5.75.85.9

66.16.26.36.46.56.6

07/0

7/20

09

13/0

7/20

09

30/0

4/20

10

19/0

7/20

10

11/0

3/20

10

01/0

6/20

12

26/0

4/20

13

28/0

8/20

13

25/0

9/20

13

15/1

0/20

13

25/0

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Stan

dard

Val

ue %

U (p

pm)

Analysis Date




10.410.610.8

1111.211.411.611.8

12

01/1

1/20

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15

Stan

dard

Val

ue %

U (p

pm)

Analysis Date




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BLANKS Denison employs a lithological blank composed of quartzite to monitor the potential for

contamination during sampling, processing, and analysis. The selected blank consists of a

material that contains lower contents of U3O8 than the sample material but is still above the

detection limit of the analytical process. Due to the sorting of the samples submitted for

assay by SRC based on radioactivity, the blanks employed must be inserted by the SRC

after this sorting takes place, in order to ensure that these materials are ubiquitous

throughout the range of analytical grades. In effect, if the individual geologists were to

submit these samples anonymously, they would invariably be relegated to the minimum

radioactive grade level, preventing their inclusion in the higher radioactive grade analyses

performed by SRC. Figure 11-7 shows results of analyses of blank samples. It can be seen

that most are below the upper limit of 0.013% U3O8, with a maximum analysis of 0.024%

U3O8.

FIELD ASSAY DUPLICATES Analyses of duplicate samples are a mandatory component of quality control. Duplicates are

used to evaluate the field precision of analyses received, and are typically controlled by rock

30

31

32

33

34

35

3607

/07/

2009

28/0

7/20

09

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1/20

15

Stan

dard

Val

ue %

U (p

pm)

Analysis Date




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heterogeneity and sampling practices. Core duplicates are prepared by collecting a second

sample of the same interval, through splitting the original sample, or other similar technique,

and are submitted as an independent sample. Duplicates are typically submitted at a

minimum rate of one per 20 samples in order to obtain a collection rate of 5%. The collection

may be further tailored to reflect field variation in specific rock types or horizons. Figure 11-8

shows results of analyses of field core duplicates plotted against original analyses. It can be

seen that results are satisfactory with a correlation coefficient of 98%.

FIGURE 11-7 BLANK SAMPLE ANALYSES RESULTS

00.005

0.010.015

0.020.025

0.030.035

0.04

07/0

7/20

0926

/08/

2009

13/0

1/20

1030

/04/

2010

05/0

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/07/

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/11/

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1/20

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/04/

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/08/

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/09/

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/02/

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/05/

2015

09/0

1/20

15

Stan

dard

Val

ue %

U (p

pm)

Analysis Date

Standard Contol Chart2011_Blank - U3O8 per AR_ICP


Blank Aveage BLANK_STD_LL BLANK_STD_UL Blank Assay

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FIGURE 11-8 FIELD DUPLICATE ANALYSES

SRC INTERNAL QA/QC PROGRAM The SRC laboratory has a Quality Assurance program dedicated to active evaluation and

continual improvement in the internal quality management system. The laboratory is

accredited by the Standards Council of Canada as an ISO/IEC 17025 Laboratory for Mineral

Analysis Testing and is also accredited ISO/IEC 17025:2005 for the analysis of U3O8. The

laboratory is licensed by the Canadian Nuclear Safety Commission (CNSC) for possession,

transfer, import, export, use, and storage of designated nuclear substances by CNSC

Licence Number 01784-1-09.3. As such, the laboratory is closely monitored and inspected

by the CNSC for compliance.

All analyses are conducted by SRC, which has specialized in the field of uranium research

and analysis for over 30 years.

SRC is an independent laboratory, and no associate, employee, officer, or director of

Denison is, or ever has been, involved in any aspect of sample preparation or analysis on

samples from the Gryphon or Phoenix deposits.

y = 1.004x + 0.1258R² = 0.9857

0

10

20

30

40

50

60

70

80

90

0 10 20 30 40 50 60 70 80 90

U3O

8As

say

Fiel

d Du

plic

ate

(%)

U3O8 Assay (%)

U3O8 Field Duplicate (%) vs. U3O8 Assay (%)

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The SRC uses a Laboratory Management System (LMS) for Quality Assurance. The LMS

operates in accordance with ISO/IEC 17025:2005 (CAN-P-4E) “General Requirements for

the Competence of Mineral Testing and Calibration Laboratories” and is also compliant to

CAN-P-1579 “Guidelines for Mineral Analysis Testing Laboratories”. The laboratory

continues to participate in proficiency testing programs organized by CANMET

(CCRMP/PTP-MAL).

All instruments are calibrated using certified materials. Quality control samples were

prepared and analyzed with each batch of samples. Within each batch of 40 samples, one to

two quality control samples were inserted. Five U3O8 reference standards are used: BLA2,

BL3, BL4A (Figure 11-9), BL5, and SRCUO2 which have concentrations of 0.502%, 1.21%

U3O8, 0.148% U3O8, 8.36% U3O8, and 1.58% U3O8, respectively. One in every 40 samples is

analyzed in duplicate; the reproducibility of this is 5%. Before the results leave the

laboratory, the standards, blanks, and split replicates are checked for accuracy, and issued

provided the senior scientist is fully satisfied. If for any reason there is a failure in an

analysis, the sub-group affected will be re-analyzed, and checked again. A Corrective Action

Report will be issued and the problem is investigated fully to ensure that any measures to

prevent the re-occurrence can and will be taken. All human and analytical errors are, where

possible, eliminated. If the laboratory suspects any bias, the samples are re-analyzed and

corrective measures are taken.

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FIGURE 11-9 BLA4 ANALYSES

Quality control samples (reference materials, blanks, and duplicates) are included with each

analytical run, based on the rack sizes associated with the method. The rack size is the

number of samples (including QC samples) within a batch. Blanks are inserted at the

beginning, standards are inserted at random positions, and duplicates are analyzed at the

end of the batch. Quality control samples are inserted based on the analytical rack size

specific to the method (Table 11-1).

0.14

0.145

0.15

0.155

0.1625

/03/

2014

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/03/

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2015

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2015

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9/20

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/09/

2015

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dard

Val

ue %

U (p

pm)

Analysis Date

Standard Contol ChartBLA4 - U3O8 per AR_ICP


BL4A Average BL4A_STD_UL BLA4_STD_LL BLA4 Assay

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TABLE 11-1 QUALITY CONTROL SAMPLE ALLOCATIONS Denison Mines Corp. – Wheeler River Property

Rack Size

Methods Quality Control Sample Allocation

20 Specialty methods including specific gravity, bulk density, and acid insolubility

2 standards, 1 duplicate, 1 blank

28 Specialty fire assay, assay-grade, umpire and concentrate methods

1 standard, 1 duplicate, 1 blank

40 Regular AAS, ICP-AES and ICP-MS methods 2 standards, 1 duplicate, 1 blank

84 Regular fire assay methods 2 standards, 3 duplicates, 1 blank

EXTERNAL LABORATORY CHECK ANALYSIS In addition to the QA/QC described above, Denison sends one in every 25 samples to the

SRC’s Delayed Neutron Counting (DNC) laboratory, a separate facility located at SRC

Analytical Laboratories in Saskatoon, to compare the uranium values using two different

methods, by two separate laboratories.

The DNC method is specific for uranium and no other elements are analyzed by this

technique. The DNC system detects neutrons emitted by the fission of U-235 in the sample,

and the instrument response is compared to the response from known reference materials to

determine the concentration of uranium in the sample. In order for the analysis to work, the

uranium must be in its natural isotopic ratio. Enriched or depleted, uranium cannot be

analyzed accurately by DNC.

There are 85 assay pairs that used both ICP-OES Total Digestion and the DNC assay

technique. Figure 11-10 shows the correlation between the SRC Geoanalytical and the SRC

DNC laboratories. It can be seen that correlation is excellent. Uranium grades obtained with

the DNC technique were used only as check assays and were not directly used for Mineral

Resource estimation.

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FIGURE 11-10 U3O8 DNC VERSUS ICP-OES ASSAY VALUES

SECURITY AND CONFIDENTIALITY SRC considers customer confidentially and security to be of utmost importance and takes

appropriate steps to protect the integrity of sample processing at all stages from sample

storage and handling to transmission of results. All electronic information is password

protected and backed up on a daily basis. Electronic results are transmitted with additional

security features. Access to SRC’s premises is restricted by an electronic security system.

The facilities at the main laboratory are regularly patrolled by security guards 24 hours a day.

After the analyses are completed, analytical data are securely sent using electronic

transmission of the results, by SRC to Denison. The electronic results are secured using

WINZIP encryption and password protection. These results are provided as a series of

Adobe PDF files containing the official analytical results and a Microsoft Excel spreadsheet

file containing only the analytical results.

In RPA’s opinion, sample preparation, security, and analytical procedures meet industry

standards, and the QA/QC program as designed and implemented by Denison is adequate;

y = 1.0191x + 0.0638R² = 0.9988

0

10

20

30

40

50

60

70

80

90

0 10 20 30 40 50 60 70 80 90

U3O

8FI

nal (

%)

U3O8 DNC (%)

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consequently, the assay results within the drill hole database are suitable for use in a Mineral

Resource estimate.

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12 DATA VERIFICATION RPA reviewed and verified the resource database used to estimate the Mineral Resources

for both the Phoenix and Gryphon deposits. The verification included a review of the QA/QC

methods and results, verifying assay certificates against the database assay table, standard

database validation tests, and two site visits.

Denison has developed and documented several QA/QC procedures and protocols for all

exploration projects operated by Denison. The review of the QA/QC program and results is

presented in Section 11, Sample Preparation, Analyses and Security. RPA reviewed

Denison’s procedures and protocols and considers them to be reasonable and acceptable

SITE VISIT AND CORE REVIEW Dr. Roscoe visited the Property on June 16, 2014 in connection with the Phoenix deposit

Mineral Resource estimate and held discussions with technical personnel in RPA’s Toronto

office on May 4, 2014. Mr. Mathisen visited the Property on March 23 to 25, 2015, during the

winter drill program in connection with the Gryphon Mineral Resource estimate. RPA visited

several drill sites and reviewed all core handling, logging, sampling, and storage procedures.

RPA examined core from several drill holes and compared observations with assay results

and descriptive log records made by Denison geologists. As part of the review, RPA verified

the occurrences of mineralization visually and by way of a hand-held scintillometer.

DATABASE VALIDATION RPA conducted audits of historic records to ensure that the grade, thickness, elevation, and

location of uranium mineralization used in preparing the current uranium resource estimate

correspond to mineralization. RPA performed the following digital queries. No significant

issues were identified.

• Header table: searched for incorrect or duplicate collar coordinates and duplicate holeIDs.

• Survey table: searched for duplicate entries, survey points past the specifiedmaximum depth in the collar table, and abnormal dips and azimuths.

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• Core recovery table: searched for core recoveries greater than 100% or less than80%, overlapping intervals, missing collar data, negative widths, and data points pastthe specified maximum depth in the collar table.

• Lithology and Probe tables: searched for duplicate entries, intervals past the specifiedmaximum depth in the collar table, overlapping intervals, negative widths, missingcollar data, missing intervals, and incorrect logging codes.

• Geochemical and assay table: searched for duplicate entries, sample intervals pastthe specified maximum depth, negative widths, overlapping intervals, sampling widthsexceeding tolerance levels, missing collar data, missing intervals, and duplicatedsample IDs.

INDEPENDENT VERIFICATION OF ASSAY TABLE The assay table contains 3,233 laboratory records. RPA verified approximately 1,010

records representing 30% of the data for uranium values against 39 different laboratory

certificates. No discrepancies were found.

Based on the data validation by Denison and RPA and the results of the standard, blank, and

duplicate analyses, RPA is of the opinion that the assay database is of sufficient quality for

Mineral Resource estimation.

DISEQUILIBRIUM Radioactive isotopes lose energy by emitting radiation and transition to different isotopes in a

“decay series” or “decay chain” until they eventually reach a stable non-radioactive state.

Decay chain isotopes are referred to as “daughters” of the “parent” isotope. When all the

decay products are maintained in close association with uranium-238 for the order of a

million years, the daughter isotopes will be in equilibrium with the parent. Disequilibrium

occurs when one or more decay products is dispersed as a result of differences in solubility

between uranium and its daughters, and/or escape of radon gas.

Knowledge of, and correction for, disequilibrium is important for deposits for which the grade

is measured by gamma-ray probes, which measure daughter products of uranium.

Disequilibrium is considered positive when there is a higher proportion of uranium present

compared to daughters. This is the case where decay products have been transported

elsewhere or uranium has been added by, for example, secondary enrichment. Positive

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disequilibrium has a disequilibrium factor which is greater than 1.0. Disequilibrium is

considered negative where daughters are accumulated and uranium is depleted. This so

called “negative” disequilibrium has a disequilibrium factor of less than 1.0 but not less than

zero.

Disequilibrium is determined by comparing uranium grades measured by chemical analyses

with the “gamma only” radiometric grade of the same samples measured in a laboratory.

There are practical difficulties in comparing chemical analyses of uranium from drill hole

samples with corresponding values from borehole gamma logging, because of the difference

in sample size between drill core (average grades in core or chip samples) and radiometric

probe measurements (gamma response from spheres of influence up to one metre in

diameter). Also, any probe calibration (and/or assay) error can be misinterpreted as

disequilibrium. If the gamma radiation emitted by the daughter products of uranium is in

balance with the actual uranium content of the measured interval (assay), then uranium

grade can be calculated solely from the gamma intensity measurement.

Denison routinely compares borehole natural gamma data to chemical assays as part of its

QA/QC program as illustrated in the example in Figures 12-1 to 12-9 (Phoenix) and Figures

12-10 to 12-13 (Gryphon). The downhole depths for gamma results in Figures 12-1 to 12-13

have not been corrected for depth so they do not correspond exactly to the chemical assay

depths. Reasonable uranium grades can be calculated from the triple gamma probe (Geiger

Mueller, or GM, tube) empirical data up to 80%. Above 80%, the counts (the maximum count

rate is about 3,500 cps) increase very little with increased grades due to the physical

characteristics of the GM tube (Sweet and Petrie 2010). In general, radiometric grades are

somewhat lower than chemical assay grades because:

• The GM tube can become saturated at very high grades and it cannot count anyhigher.

• Some gamma rays are captured by the uranium, converted to photons, and absorbed(self-absorption), i.e., they are not available to the detector.

Denison and RPA carried out a check of the digital probe database used for resource

estimation by verifying the resource database against original assay data. Denison and RPA

concluded that in instances where core recovery was less than 80%, radiometric data could

be substituted for chemical assays and that the assay database was of sufficient quality for

Mineral Resource estimation.

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FIGURE 12-1 WR-318 RADIOMETRIC VS. ASSAY % U3O8 VALUES

0.0

10.0

20.0

30.0

40.0

50.0

60.0

400 401 402 403 404 405 406 407 408 409 410

%eU

3O8

vs. %

U3O

8

Depth (m)

GM 12 Gamma (%eU3O8) Assay (%U3O8)

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0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

405 406 407 408 409 410 411 412 413 414 415

%eU

3O8

vs. %

U3O

8

Depth (m)


0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

402 403 404 405 406 407 408 409 410 411 412 413

%eU

3O8

vs. %

U3O

8

Depth (m)


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0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

408 409 410 411 412 413 414 415 416 417 418

%eU

3O8

vs. %

U3O

8

Depth (m)


0.0

10.0

20.0

30.0

40.0

50.0

60.0

70.0

80.0

90.0

404 405 406 407 408 409 410 411 412 413 414 415

%eU

3O8

vs. %

U3O

8

Depth (m)


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0

10

20

30

40

50

60

70

80

90

100

395 397 399 401 403 405 407 409 411 413 415

%eU

3O8

vs. %

U3O

8

Depth (m)


0

10

20

30

40

50

60

70

80

90

100

390 392 394 396 398 400 402 404 406 408 410 412 414 416 418 420

%eU

3O8

vs. %

U3O

8

Depth (m)


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0

10

20

30

40

50

60

70

80

90

100

405 406 407 408 409 410 411 412 413 414 415

Gra

de U

3O8

(%)

Depth (m)


0

10

20

30

40

50

395 396 397 398 399 400 401 402 403 404 405 406 407 408 409 410

%eU

3O8

vs. %

U3O

8

Depth (m)


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FIGURE 12-11 WR-573D1 RADIOMETRIC VS. ASSAY % U3O8 VALUES

0

5

10

15

20

25

30

35

40

45

50

757 758 759 760 761 762 763 764 765

%eU

3O8

vs. %

U3O

8

Depth (m)

Assay (%U3O8) GM 12 Gamma (%eU3O8)

0

10

20

30

40

50

60

70

545 546 547 548 549 550 551 552 553 554 555

%eU

3O8

vs. %

U3O

8

Depth (m)


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FIGURE 12-13 WR-584B RADIOMETRIC VS. ASSAY % U3O8 VALUES

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

9.00

10.00

755.00 757.00 759.00 761.00 763.00 765.00 767.00 769.00 771.00 773.00 775.00

%eU

3O8

vs. %

U3O

8

Depth (m)


0

5

10

15

20

25

640 641 642 643 644 645 646 647 648 649 650

%eU

3O8

vs. %

U3O

8

Depth (m)


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13 MINERAL PROCESSING AND METALLURGICAL TESTING Preliminary metallurgical testing was carried out on a composite sample from the Phoenix

deposit by the Saskatchewan Research Council in Saskatoon under the direction of Chuck

Edwards, Director of Metallurgy at AMEC Americas Limited. A representative composite

sample consisting of 17.5 kg of split drill core from the Phoenix deposit was subjected to

QEMSCAN analysis, preliminary sulphuric acid leaching tests, leach residue settling tests,

solvent extraction tests, and a yellowcake production test. The grade of the sample was

19.7% U3O8, approximately the same as the average grade of the deposit.

Key points from the test work are summarized below:

• Uraninite is the primary uranium mineral.

• Deleterious element concentrations are very low.

• Over 95% of the uraninite was exposed in all size fractions, indicating that a relatively coarse grind can be planned for leaching.

• Leach tests suggest that over 99.5% of the uranium can be extracted in 8-12 hours at a temperature of 50°C, atmospheric pressure, and addition of an oxidant.

• Acid consumption was low at 1.6-1.7 kg/lb U3O8.

• Solvent extraction is effective to selectively extract and purify uranium.

• A high purity yellowcake product was produced that met all ASTM C967-13 specifications.

Preliminary metallurgical testing for the Gryphon deposit is near finalization. The Gryphon

deposit is expected to have similar high extraction efficiencies based on observation of drill

core, petrographic work, and geochemical data.

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14 MINERAL RESOURCE ESTIMATE RPA has estimated Mineral Resources for the Phoenix and Gryphon deposits based on

results of several surface diamond drilling campaigns from 2008 to 2015. The Phoenix

deposit consists of zone A and zone B at the Athabasca unconformity, and zone A basement

mineralization which is immediately below the north part of zone A. The Gryphon deposit

consists of several stacked lenses in the basement, and is located approximately three

kilometres northwest of the Phoenix deposit.

Table 14-1 summarizes the Mineral Resource estimate, of which Denison’s share is 60%.

The effective date of the Mineral Resource estimate is September 25, 2015. The Mineral

Resource estimate for Phoenix was reported in a previous NI 43-101 Technical Report

(Roscoe 2014) dated June 17, 2014 with and effective date of May 28, 2014, and there has

been no change to the Phoenix Mineral Resource estimate since that time. Details of the

estimation methodology follow below.

TABLE 14-1 MINERAL RESOURCE ESTIMATE FOR THE WHEELER RIVER PROJECT AS OF SEPTEMBER 25, 2015 (100% BASIS)


Category Deposit Tonnes Grade (% U3O8)

Million lbs U3O8

Indicated Phoenix - Zone A 147,200 19.81 64.3 Indicated Phoenix - Zone B 19,200 13.94 5.9 Total Indicated 166,400 19.14 70.2 Inferred Phoenix - Zone B 5,500 3.30 0.4 Inferred Phoenix - Zone A Basement 3,100 10.24 0.7 Inferred Gryphon Deposit 834,000 2.31 43.0 Total Inferred 842,600 2.37 44.1

Notes:



assumptions and a price of US$50 per lb U3O8. 4. High grade composites are subjected to a high grade search restriction without capping at Phoenix. 5. High grade mineralization was capped at 30% U3O8 with no search restrictions at Gryphon. 6. Bulk density is derived from grade using a formula based on 196 measurements at Phoenix and 65


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RPA is not aware of any environmental, permitting, legal, title, taxation, socio-economic,

marketing, political, or other relevant factors that could materially affect the Mineral Resource

estimate.

DRILL HOLE DATABASE The Property drill hole database includes drilling results from 2008 to 2015, which comprise

433 diamond drill holes totalling 222,154 m, of which 196 drill holes totalling 89,835 m have

delineated the Phoenix deposit and 55 holes totalling 40,041 m have delineated the Gryphon

deposit. Zone A at Phoenix is the northeastern lens and strikes N52°E and zone B consists

of two subzones, B1 and B2, which form the southwestern part of the Phoenix deposit. Zone

A basement mineralization is within a narrow fracture zone that extends below the northern

end of zone A. The Gryphon deposit is a series of stacked basement mineralized lenses

striking N20oE.

Upon completion of the initial data processing, the borehole data as well as radiometric

logging information was uploaded into VULCAN software. Table 14-2 lists details of the

VULCAN database used for the resource estimate. Section 12, Data Verification, describes

the verification steps made by RPA. In summary, no discrepancies were identified and RPA

is of the opinion that the drill hole database is valid and suitable to estimate Mineral

Resources for the Phoenix and Gryphon deposits.

TABLE 14-2 VULCAN DATABASE RECORDS Denison Mines Corp. – Wheeler River Property

Table Name Number of Records

Gryphon Phoenix Collar 69 253 Survey 857 2,879 Stratigraphy 934 2,632 Assay Values 1,019 2,111 Radiometric Values (% eU3O8) 118,048 166,287 Block Model 1m Composites in Wireframes 419 703

A Deposit UC – Composites 471 B Deposit UC – Composites 92

A Deposit Basement – Composites 140

Drill holes at Phoenix were completed on northwest-southeast oriented sections spaced at

approximately 25 m intervals along strike with a drill hole spacing of approximately 10 m

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along the sections. Earlier holes were drilled at steep angles to the northwest and later holes

were collared vertically. Figure 14-1 shows zones A and B with locations of drill holes.

Figure 14-2 shows the location of the zone A basement mineralization.

For Gryphon, drill holes were completed on northwest-southeast oriented sections spaced at

approximately 50 m intervals along strike with a drill hole spacing of approximately 50 m

along the sections. Figure 14-3 shows the locations of drill holes at Gryphon.

ZONE A

ZONE B1

ZONE B2

Drill Hole Trace

N

0 50

Metres

100 150 200



Phoenix DepositZones A and B

Drill Hole Locations

Denison Mines Corp.


Figure 14-1

14

4-

ww

w.rp

acan

.co

m

Drill Hole Trace

ZONE A BASEMENT

N

0 25

Metres

50 75 100



Phoenix Deposit Zone ABasement Drill Hole Locations

Denison Mines Corp.


Figure 214-

15

4-

ww

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Legend:

Quartzite

Drill Hole Collar

Graphitic Pelite

Pelite

Pegmatite

Property Boundary

0 500

Metres

1000 1500 2000

N

November 2015

Gryphon DepositDrill Hole Locations


Denison Mines Corp.


Figure 14-3

14-6

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GEOLOGICAL INTERPRETATION AND 3D SOLIDS

PHOENIX DEPOSIT Denison has interpreted the geology, structure, and mineralized zones at Phoenix using data

from 196 diamond drill holes that penetrate the basal unconformity of the Athabasca

sandstone. Uranium mineralization occurs at the unconformity surface and in the adjacent

sandstone above and in the adjacent graphitic pelite basement rocks below the

unconformity. Zones A and B both strike approximately N52°E and are essentially

horizontal.

A regional fault, the WS fault, is spatially associated with mineralization in the Phoenix

deposit. The WS fault trends northeasterly, parallel to the mineralization, and dips

moderately to the southeast. It appears to be a steep angle reverse fault, displacing the

unconformity in the order of five metres or more upward on the southeast side. Uranium

mineralization extends outward to the southeast from the WS fault, suggesting that the

primary controls on the Phoenix deposit are the intersection of the WS fault with the

unconformity and graphitic pelite in the basement. Some uranium mineralization occurs on

the northwest side of the WS fault along the unconformity which is at lower elevation,

however, it is limited in extent to the northwest. Other faults are present in the Phoenix

deposit sub-parallel to the WS fault but with lesser vertical displacements. Some cross faults

with easterly or southeasterly trends are interpreted, with displacements in the order of five

metres or more.

The zone A basement mineralization is restricted to a narrow (<3 m) fracture zone extending

approximately 20 m below the northern end of zone A. The fracture zone runs parallel to the

strike of zone A at approximately N52°E and dips at -65° to the southeast. The axis of the

fracture is centred along drill holes WR-503, WR-403, and WR-506 and is interpreted as

splay faulting associated with the WS fault described previously.

Denison developed three dimensional (3D) wireframe models, which were reviewed and

accepted by RPA for the Phoenix deposit zones A and B. The models represent grade

envelopes using the geological interpretation described above as guidance. The wireframes

consisted of a lower grade (LG) domain and a higher grade (HG) domain. For the LG

wireframe, a threshold grade of 0.05% U3O8 was used as a guide. For zone A, the threshold

grade for inclusion in the HG domain was approximately 20% U3O8, although lower grades

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were incorporated in places to maintain continuity and to maintain a minimum thickness of

two metres. For zone B, the minimum threshold for the HG domain was approximately 10%

U3O8 over a minimum thickness of two metres. Figures 14-4 to 14-6 are cross sections of

zone A showing drill holes with one metre composite grades and the outlines of the HG and

LG domains. Figure 14-7 shows the same for zone B. Figure 14-8 is a longitudinal view of

the zone A basement domain.

The wireframe model developed for zone A is approximately 380 m long, 36 m wide, and

ranges in thickness from two metres to 17 m with an average thickness of five metres. The

zone B wireframe model measures approximately 290 m long, averages 19 m wide, and is

approximately three metres thick. The wireframes were used to assign domain codes to the

blocks in the block model and for generating and coding composited assays.

Drill Hole

3 8

Legend:

1 metre composite withgrade in % U O

1.0714.40

11.251.08

0 2 10

Metres

4 6 8

November 2015

Denison Mines Corp.

Northern Saskatchewan, CanadaWheeler River Property

Phoenix Deposit, Zone ATypical Cross Section Including

WR-435 with HG and LG Domains

Figure -414

19

4-

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Drill Hole

3 8

Legend:


1.0714.40

11.251.08

0 2 10

Metres

4 6 8

November 2015


Denison Mines Corp.




Figure -514

110

4-

ww

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Drill Hole

3 8

Legend:


1.0714.40

11.251.08

0 2 10

Metres

4 6 8

November 2015




Denison Mines Corp.


Figure -614

111

4-

ww

w.rp

acan

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Drill Hole

3 8

Legend:


1.0714.40

11.251.08

0 2 10

Metres

4 6 8

November 2015

Denison Mines Corp.


Phoenix Deposit, Zone BTypical Cross Section Including


Figure -714

112

4-

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Drill Hole

3 8

Legend:


1.0714.40

11.251.08

0 2 10

Metres

4 6 8

November 2015

Denison Mines Corp.

Phoenix DepositZone A Basement

Longitudinal Section


Figure -814

113

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GRYPHON DEPOSIT Wireframe models of mineralized zones were used to constrain the block model grade

interpolation process, based on a total of 55 holes. RPA built the wireframe models using 3D

polylines on northeast looking vertical sections spaced approximately 12.5 m apart.

Polylines were “snapped” to assay intervals along the drill hole traces such that the sectional

interpretations “wobbled” in 3D space. Polylines were joined together in 3D and the

continuity was checked using a longitudinal section and level plans.

A threshold grade of 0.05% U3O8 and a minimum core length of two metres was used as a

guide, resulting in a series of eight stacked lenses or domains of variable thicknesses that

plunge 35° to 60° at 035° to 040° northeast, and dip 25° to 50° to the southeast (Table 14-3

and Figures 14-9 and 14-10). The mineralized wireframes were subsequently clipped to

include only drill holes with intersections greater than 0.2% U3O8 over a minimum thickness

of two metres. The stacked lenses form a zone of mineralization measuring approximately

280 m long (along plunge) by 113 m wide (across plunge) and remain open both up and

down plunge. Wireframes were assigned to zones as identified by Denison disclosures.

TABLE 14-3 SUMMARY OF GRYPHON WIREFRAME MODELS Denison Mines Corp. – Wheeler River Property

Zone Wireframe Name Points Triangles Surface Area Volume Tonnage

Block Model Code

A1 rpa_gryphon_min_a1_1.00t 893 1,782 98,989 169,823 382,731 1 A2 rpa_gryphon_min_a2_1.00t 810 1,616 62,098 72,158 162,622 2 A3 rpa_gryphon_min_a3_1.00t 188 372 9,539 8,467 19,082 3 B1 rpa_gryphon_min_b1_1.00t 525 1,046 46,301 63,537 143,192 4 B2 rpa_gryphon_min_b3_1.00t 367 730 30,191 36,606 82,499 5 B3 rpa_gryphon_min_b2_1.00t 205 406 8,855 11,467 25,844 6 C1 rpa_gryphon_min_c1_1.00t 402 800 28,343 30,812 69,440 8 C2 rpa_gryphon_min_c2_1.00t 511 1,018 13,895 12,053 27,163 9 D1 rpa_gryphon_min_d1.00t 65 126 6,779 6,330 14,267 10 D2 rpa_gryphon_min_d2.00t 46 88 3,121 2,912 6,563 11 D3 rpa_gryphon_min_d3.00t 14 24 1,215 1,046 2,357 12 D4 rpa_gryphon_min_d4.00t 24 44 800 637 1,435 13 Total 4,050 8,052 310,127 415,848 937,196

Notes: • A-Series (A1, A2, and A3): represent the mineralized zones on the hanging wall (Upper Zone) of the

quartz-pegmatite assemblage (wireframes 1, 2 and 3)• B-Series (B1, B2, and B3): represent the mineralized zones within the quartz-pegmatite assemblage

(wireframes 4, 5, and 6)• C-Series (C1 and C2): represent the mineralized zones along the foot wall (Lower Zone) of the quartz-

pegmatite assemblage (wireframes 8 and 9)

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• D-Series (D1, D2, D3, and D4): represent four low grade mineralized zones (wireframes 10, 11, 12 and 13), which do not have enough drilling to be included in the resource estimate

Mineral Resources were estimated for the A, B, and C Series lenses, and not for the D

Series, which were considered to have insufficient drilling. The A1 and C1 domains

collectively make up nearly 69% of the contained pounds of U3O8 in the Mineral Resource.

RPA conducted audits of the wireframes to ensure that the wireframes used in preparing the

current resource estimate correspond to the reported mineralization. Quality control

measures and the data verification procedures repeated in 2015 included the following:

• Check for overlapping wireframes to determine possible double counting.

• Check mineralization/wireframe extensions beyond last holes to see if they are reasonable and consistent.

• Check for reasonable compositing intervals.

• Check that composite intervals start and stop at wireframe boundaries.

• Validate the solids for closure and consistent topology, and check that the triangles intersect properly (crossing). Any issues found were corrected with the appropriate Vulcan utility to ensure accurate volume and grade estimates.

Strat Group

Unconformity

Manitou Falls Fm.

Grade (U O %)3 8

< 0. %05

0. % - 0.8 %2

0.8 % - 5 %

5 % - 10 %

10 % - 20 %

20 % - 30 %

30 % - 0 %6

> 0 %6

0. % - 0. %05 2

Overburden

Quartzite

Graphitic Pelite

Pegmatite

Pelite

0 25

Metres

50 75 100

November 2015


Gryphon DepositGeologic Cross Section

Schematic of Mineralization

Denison Mines Corp.


Figure 14-9

14-1

6

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Grade (U O %)3 8

< 0. %05

0. % - 0.8 %2

0.8 % - 5 %

5 % - 10 %

10 % - 20 %

20 % - 30 %

30 % - 0 %6

> 0 %6

0. % - 0. %05 2

Strat Group

Overburden

Quartzite

Graphitic Pelite

Pegmatite

Pelite

Unconformity

Manitou Falls Fm.

0 25

Metres

50 75 100

November 2015

Looking NE


Gryphon DepositWireframes at Drill

INDEX LINE 5000 Cross Section

Denison Mines Corp.


Figure 14-10

14-1

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BULK DENSITY Bulk density is used to convert volume to tonnage and to weight the block grade estimates.

In high grade uranium deposits such as Gryphon, bulk density varies with grade due to the

very high density of pitchblende/uraninite compared to host lithologies. Bulk density also

varies with clay alteration and in situ rock porosity. For Mineral Resource estimates of high

grade uranium deposits, it is important to estimate bulk density values throughout the deposit

and to weight grade values by density since small volumes of high grade material contain

large masses of uranium oxide.

Bulk density is determined by Denison with specific gravity (SG) measurements on drill core.

SG is calculated as: weight in air/(weight in air – weight in water). Under all reasonable

conditions, SG (a unitless ratio) is equivalent to density in t/m3.

PHOENIX DEPOSIT From 2012 to 2014, Denison completed a program of dry bulk density sampling from

diamond drill core in order to establish the relationship between bulk density and grade for

the Phoenix deposit zones A and B. Dry bulk density samples were selected from the main

mineralized zones to represent local major lithologic units, mineralization styles, and

alteration types. Samples were collected from half split core, which had been previously

retained in the core box after geochemical sampling. Samples were tagged and placed in

sample bags on site, then shipped to the SRC in Saskatoon, Saskatchewan. In total, SRC

has performed SG measurements on a total of 196 samples; 162 from zone A and 34 from

zone B.

Denison carried out correlation analyses of the bulk density values against uranium grades

which indicated a strong relationship between density and uranium grade (%U3O8) shown in

Figure 14-11. The relationship can be represented by the following polynomial formula which

is based on a regression fit.

y = 0.0008x2 – 0.0077x + 2.3361

where y is dry bulk density (g/cm3) and x is the uranium grade in %U3O8. In some cases

when the samples are very clay rich, core fatigue (sample crumbles) prevented the wax from

being applied and SG was calculated using the wet/dry method only. Figure 14-12 shows a

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strong correlation between the methodologies and RPA is satisfied that either methodology is

suitable for determining SG.

FIGURE 14-11 LOGARITHMIC PLOT OF DRY BULK DENSITY VERSUS URANIUM GRADE - PHOENIX DEPOSIT

y = 0.0008x2 - 0.0077x + 2.3361R² = 0.8166

0

1

2

3

4

5

6

7

8

9

0.001 0.01 0.1 1 10 100

Deni

sty

(g/c

m3 )

Grade (%U3O8)

SGwax_ratio_CALC WR-PA WR-PB Poly. (SGwax_ratio_CALC)

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FIGURE 14-12 DRY BULK DENSITY WAX VERSUS DRY/WET METHODS - PHOENIX DEPOSIT

The regression curve in Figure 14-11 is relatively flat at a grade less than 10% U3O8, with

density relatively constant at 2.33 g/cm3. At grades greater than 20%, dry bulk density

increases with higher uranium grades. There are a number of strongly mineralized samples

that have low dry bulk densities and vice versa, which results in significant scatter in dry bulk

density values. The lower bulk density values associated with strongly mineralized samples

may be attributed to the amount of clay alteration in the samples. Generally, clay alteration

causes decomposition of feldspar and mafic minerals with resultant replacement by lighter

clay minerals as well as loss of silica from feldspar that lowers the dry bulk density of the

rock.

Denison has estimated a dry bulk density value for each grade value in the drill hole

database by using the polynomial formula shown above. In RPA’s opinion, the SG sampling

methods and resulting data are suitable for Mineral Resource estimation at Phoenix.

y = 1.029x - 0.2928R² = 0.9845

0

1

2

3

4

5

6

7

8

9

0 1 2 3 4 5 6 7 8 9

SG W

ax (g

/cm

3 )

SG Core (g/cm3)

SG Core vs. WAX Linear (SG Core vs. WAX)

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GRYPHON DEPOSIT Based on 65 dry bulk density determinations, Denison developed a formula relating bulk

density to grade which was used to assign a density value to each assay. Bulk density

values were used to weight grades during the resource estimation process and to convert

volume to tonnage.

Denison carried out correlation analyses of the bulk density values against uranium grades

(%U3O8) as shown in Figure 14-13. The relationship can be represented by the following

polynomial formula which is based on a regression fit.

y = 4E-05x2 + 0.0166x + 2.2537

where y is dry bulk density (g/cm3) and x is the uranium grade in %U3O8. The available SG

values for the assay data were reviewed and accepted by RPA and used to assign bulk

density values to each sample.

FIGURE 14-13 LOGARITHMIC PLOT OF DRY BULK DENSITY VERSUS URANIUM GRADE - GRYPHON DEPOSIT

y = 0.0004x2 + 0.0166x + 2.2537R² = 0.9046

0

1

2

3

4

5

6

0.0001 0.001 0.01 0.1 1 10 100

Dens

ity (g

/cm

3)

Grade (%U3O8)

SGwax_ratio_CALC Poly. (SGwax_ratio_CALC)

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Denison has estimated a dry bulk density value for each grade value in the drill hole

database by using the polynomial formula shown above. In RPA’s opinion, the SG sampling

methods and resulting data are suitable for Mineral Resource estimation at Gryphon.

STATISTICS

TREATMENT OF HIGH GRADE VALUES Where the assay distribution is skewed positively or approaches log normal, erratic high

grade assay values can have a disproportionate effect on the average grade of a deposit.

One method of treating these outliers in order to reduce their influence on the average grade

is to cut or cap them at a specific grade level. In the absence of production data to calibrate

the cutting level, inspection of the assay distribution can be used to estimate a “first pass”

cutting level.

PHOENIX DEPOSIT Although the Phoenix deposit is a high grade uranium deposit, adequate sample support, the

use of high grade domains, and lack of apparent high grade outliers made high grade

capping unnecessary. The influence of high grade values, however, was restricted during

the block estimation process as discussed below under interpolation parameters.

GRYPHON DEPOSIT Assay values located inside the wireframe models were tagged with domain identifiers and

exported for statistical analysis. Results were used to help verify the modelling process.

Basic statistics by domain are summarized in Table 14-4.

TABLE 14-4 DESCRIPTIVE STATISTICS OF GRYPHON URANIUM ASSAY BY DOMAIN Denison Mines Corp. – Wheeler River Property

Descriptive Statistic Zone A1 Zone A2 Zone A3 Zone B1 Count 281 102 17 190 Mean 2.46 0.76 0.55 0.58 Median 0.25 0.08 0.16 0.09 Std. Dev. 6.22 1.75 1.14 2.00 Variance 38.73 3.05 1.30 4.00 Kurtosis 17.03 8.02 6.38 46.77 Skewness 4.00 2.94 2.73 6.44 Range 40.60 8.67 4.56 17.10 Minimum 0.00 0.00 0.00 0.00 Maximum 40.60 8.67 4.56 17.10

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Coefficient of Variation 2.53 2.29 2.06 3.47 Descriptive Statistic Zone B2 Zone B3 Zone C1 Zone C2 Count 49 24 46 15 Mean 2.60 3.89 4.75 0.26 Median 0.25 0.43 0.42 0.16 Std. Dev. 4.77 8.37 10.39 0.29 Variance 22.79 70.12 107.91 0.09 Kurtosis 3.31 6.73 5.68 0.47 Skewness 2.09 2.70 2.60 1.21 Range 18.80 36.00 42.50 1.01 Minimum 0.00 0.00 0.00 0.00 Maximum 18.80 36.00 42.50 1.01 Coefficient of Variation 1.84 2.15 2.19 1.14

Review of the resource assay histogram and log normal probability plots within the wireframe

domains and a visual inspection of high grade values on vertical sections suggest cutting

erratic grade values to 30% (Figure 14-14), which only impacts zones A1, B3, and C1.

Results of the capping impacted 10 (1.2%) values out of 834 assays. Table 14-5 lists

descriptive statistics for the domains affected by cutting.

TABLE 14-5 STATISTICS OF GRYPHON CAPPED ASSAYS BY DOMAIN Denison Mines Corp. – Wheeler River Property

Zone A1 Zone B3 Zone C1 Descriptive Statistic Raw Cap Raw Cap Raw Cap Count 281 281 24 24 46 46 Mean 2.46 2.34 3.89 3.64 4.75 4.20 Median 0.25 0.25 0.43 0.43 0.42 0.42 Std. Dev. 6.22 5.61 8.37 7.61 10.39 8.66 Variance 38.73 31.49 70.12 57.91 107.91 75.04 Kurtosis 17.03 13.45 6.73 6.21 5.68 4.36 Skewness 4.00 3.61 2.70 2.56 2.60 2.36 Range 40.60 30.00 36.00 30.00 42.50 30.00 Minimum 0.00 0.00 0.00 0.00 0.00 0.00 Maximum 40.60 30.00 36.00 30.00 42.50 30.00 Coefficient of Variation 2.53 2.39 2.15 2.09 2.19 2.06

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FIGURE 14-14 ZONE A1 LOG NORMAL PROBABILITY AND HISTOGRAM PLOT – GRYPHON DEPOSIT

.999 .999

.99 .99

.9 .9

.5 .5

.1 .1

.01 .01

.001 .0010.0001 0.001 0.01 0.1 1 10 100

Log

Nor

mal

Pro

babi

lity

%

Grade (% U3O8)

0

20

40

60

80

100

120

140

0.00

1.40

2.80

4.20

5.60

7.00

8.40

9.80

11.2

12.6

14.0

15.4

16.8

18.2

19.6

21.0

22.4

23.8

25.2

26.6

28.0

29.4

30.8

32.2

33.6

35.0

36.4

37.8

39.2

40.6

Sam

ple

Cou

nt

Grade (% U3O8)

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COMPOSITES As discussed in Section 10 Drilling and Section 11 Sample Preparation, Analyses and

Security, all drill core samples with chemical assays are 0.5 m long and all radiometric

measurements are 0.1 m long. Radiometric measurements are used in lieu of chemical

assays where core recovery is less than 80%.

Sample lengths range from 0.5 cm to 1.0 m within the wireframe models, however, 99.85%

of the samples were taken at 0.5 m intervals. Given this distribution, and considering the

width of the mineralization, RPA composited uranium grade (G), bulk density (D), and

uranium grade multiplied by density (GxD) values over one metre run-length intervals to

create a composite database for statistical analysis and block estimation purposes. Assay

grades are weighted by both sample length and density when compositing. Compositing

was restricted to within the wireframe models (hard boundaries). This can result in residual

short composites at the bottom of the wireframes. These short composites were retained if

they were between 0.5 m and 1.0 m long, and were added to the previous full length

composite if they were less than 0.5 m long. As discussed below, block estimation was done

by interpolating GxD and density and dividing them to obtain a density-weighted grade

estimate for each block.

Approximately 23% of the drill holes used for the Phoenix deposit zone A resource estimate

and approximately 25% of those used for the zone B resource estimate have radiometric

measurements. No radiometric data were used in the Gryphon resource estimate.

PHOENIX DEPOSIT Separate composite files were prepared for the zone A HG domain, zone A LG domain, zone

B HG domain, zone B LG domain, and zone A basement domain. Table 14-6 lists

descriptive statistics of composite grade and GxD for each of these domains.

Figure 14-15 shows histograms of grade for each of these domains. Figure 14-16 shows

grade versus density plots of these domains.

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TABLE 14-6 BASIC STATISTICS OF GRADE AND GXD COMPOSITES FOR PHOENIX DEPOSIT ZONES A AND B HG AND LG DOMAINS


Statistic Zone A Grade Zone B Grade Zone A GxD Zone B GxD

HG LG BSMT HG LG HG LG BSMT HG LG Mean 34.86 1.77 1.56 21.65 1.57 156.50 4.20 4.48 77.51 3.75 Standard Error 1.93 0.14 0.36 3.74 0.31 12.99 0.36 1.24 16.89 0.76 Median 31.52 0.59 0.32 17.14 0.53 107.54 1.36 0.88 43.68 1.24 Mode #N/A 0.18 0.00 #N/A 0.25 #N/A 0.42 1.93 #N/A 0.35 Standard Deviation 21.62 2.69 4.26 15.85 2.64 145.26 6.63 14.28 71.67 6.46 Sample Variance 467.56 7.23 18.12 251.25 6.99 21,101.66 43.93 203.78 5,136.66 41.74 Kurtosis -0.69 10.25 23.16 -1.02 4.65 0.77 15.12 31.86 -0.87 5.24 Skewness 0.45 2.81 4.72 0.54 2.36 1.27 3.23 5.49 0.84 2.46 Range 82.31 20.13 27.66 49.24 10.86 595.34 56.99 101.48 212.74 27.49 Minimum 0.29 0.01 0.00 1.46 0.01 0.69 0.02 0.00 3.42 0.02 Maximum 82.60 20.14 27.66 50.69 10.87 596.02 57.01 101.49 216.16 27.51 Sum 4,357.3 607.7 214.9 389.7 113.0 19,562.5 1,445.5 595.6 1,395.2 270.0 Count 125 344 138 18 72 125 344 133 18 72 Coefficient of Variation 0.62 1.52 2.73 0.73 1.68 0.93 1.58 3.19 0.92 1.72

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FIGURE 14-15 GRADE COMPOSITE HISTOGRAMS FOR PHOENIX DEPOSIT ZONES A AND B HG AND LG DOMAINS

0.00%20.00%40.00%60.00%80.00%100.00%

0

10

20

30

10 20 30 40 50 60 70 80 90 100

Freq

uenc

y

Grade

Phoenix Zone A HG Domain Grade Histogram

Frequency Cumulative %

0.00%20.00%40.00%60.00%80.00%100.00%

0

2

4

6

10 20 30 40 50 60 70 80 90 100

Freq

uenc

y

Grade

Phoenix Zone B HG Domain Grade Histogram


0.00%20.00%40.00%60.00%80.00%100.00%

0

50

100

150

1 3 5 7 9 11 13 15 17 19

Freq

uenc

y

Grade

Phoenix Zone A BSMT Domain Grade Histogram


0.00%20.00%40.00%60.00%80.00%100.00%

050

100150200250

1 3 5 7 9 11 13 15 17 19

Freq

uenc

y

Grade

Phoenix Zone A LG Domain Grade Histogram


0.00%20.00%40.00%60.00%80.00%100.00%

0

20

40

60

1 2 3 4 5 6 7 8 9 10 11 12

Freq

uenc

y

Grade

Phoenix Zone B LG Domain Grade Histogram


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FIGURE 14-16 GRADE VS. DENSITY PLOTS FOR PHOENIX DEPOSIT ZONES A AND B HG AND LG DOMAINS

y = 0.0007x2 + 0.0027x + 2.312R² = 0.9879

012345678

0 20 40 60 80 100

Dens

ity

Grade

Phoenix Zone A HG Domain

y = 0.0006x2 + 0.0093x + 2.2571R² = 0.9625

0

1

2

3

4

5

0 20 40 60

Dens

ity

Grade

Phoenix Zone B HG Domain

y = 0.0013x2 - 0.0161x + 2.3417R² = 0.8511

00.5

11.5

22.5

33.5

0 10 20 30

Dens

ity

Grade

Phoenix Zone A BSMT Domain

y = 0.0009x2 - 0.0063x + 2.3357R² = 0.7685

2.32.35

2.42.45

2.52.55

2.62.65

0 5 10 15 20 25

Dens

ity

Grade

Phoenix Zone A LG Domain

y = 0.0014x2 - 0.0083x + 2.3365R² = 0.5939

2.3

2.35

2.4

2.45

2.5

0 5 10 15

Dens

ity

Grade

Phoenix Zone B LG Domain

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GRYPHON DEPOSIT Assays were capped prior to compositing. Table 14-7 shows the composite statistics by

domain.

TABLE 14-7 DESCRIPTIVE STATISTICS OF GRYPHON DEPOSIT COMPOSITE URANIUM ASSAY BY DOMAIN

Denison Mines Corp. – Wheeler River Property Descriptive Statistic Zone A1 Zone A2 Zone A3 Zone B1 Count 131 51 4 51 Mean 2.25 0.76 0.94 0.89 Median 0.38 0.16 0.67 0.18 Std. Dev. 4.53 1.32 0.96 2.34 Variance 20.52 1.74 0.92 5.46 Kurtosis 12.36 3.74 -1.28 16.26 Skewness 3.26 2.16 0.55 4.10 Range 30.00 5.43 2.42 12.34 Minimum 0.00 0.00 0.00 0.00 Maximum 30.00 5.43 2.42 12.34 Coefficient of Variation 2.02 1.74 1.02 2.64

Zone B2 Zone B3 Zone C1 Zone C2

Count 26 15 26 15 Mean 2.33 2.76 3.48 0.19 Median 0.33 0.44 0.56 0.01 Std. Dev. 3.85 4.45 6.70 0.35 Variance 14.81 19.84 44.90 0.12 Kurtosis 1.97 1.46 3.15 5.94 Skewness 1.81 1.67 2.16 2.56 Range 13.54 14.77 24.03 1.39 Minimum 0.00 0.00 0.00 0.00 Maximum 13.54 14.77 24.03 1.39 Coefficient of Variation 1.65 1.61 1.92 1.83

VARIOGRAPHY – CONTINUITY ANALYSIS

PHOENIX DEPOSIT For zone A, RPA reviewed variograms of grade and GxD for the HG domain composite data

and grade for the LG domain composite data. Variograms were prepared in the downhole

direction, along a northeasterly strike direction, and horizontally across the strike direction.

Variograms were of fair quality considering the limited number of composite data. The

nugget effect was approximately 10% of the sill. The GxD variograms were similar to those

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of grade. The variograms suggested approximate ranges for the zone A HG domain of 2.4 m

downhole, 35 m along strike, and 10 m or less across strike; and for the zone A LG domain,

2.1 m downhole, 25 m or less along strike, and 25 m across strike. These ranges were used

to derive search ellipse dimensions for block interpolations.

GRYPHON DEPOSIT Zone specific variography has not been undertaken because the current drill hole spacing

and number of samples are not adequate to generate meaningful variograms.

INTERPOLATION PARAMETERS Three dimensional block models were constructed using Maptek Vulcan Mine Modelling

Software. The variables G, D, and GxD were interpolated using an inverse distance squared

(ID2) algorithm for each mineralized domain. Hard boundaries were employed at domain

contacts, so that composites from within a given domain could not influence block grades in

other domains. Table 14-8 shows the block model parameters and variables used.

TABLE 14-8 PHOENIX AND GRYPHON BLOCK MODEL PARAMETERS AND VARIABLES


Model name: H:\PROJECTS\2534 - Denison Mines Corp - Gryphon Deposit\Work\VULCAN_30Sept2015\wr_gryphon_sept2015_2m_capped-30

History list: wr_gryphon_sept2015_2m_capped-3014Oct2015.bhst Format: extended Structure: regular Smooth: no Number of blocks: 19,250,000 Number of variables: 13 Number of schemas: 1 Origin: 474,768.281 6,376,260.0 -400.0 Bearing/Dip/Plunge: 110.0 0.0 0.0 Offset: 550.0 700.00 1000.0

Model name: H:\PROJECTS\2299-Denison Mines Corp.-Phoenix Uranium Deposits\Work\Vulcan\Phoenix\phx5_HG_zonea_u2

History list: phx5_HG_zonea23May2014.bhst Format: extended Structure: non-regular Smooth: no

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Number of blocks: 1808 Number of variables: 12 Number of schemas: 1 Origin: 476,725.0 6,373,800.0 30.0 Bearing/Dip/Plunge: 52.0 0.0 0.0 Offset: 820.0 120.0 200.0

Model name: H:\PROJECTS\2299-Denison Mines Corp.-Phoenix Uranium Deposits\Work\Vulcan\Phoenix\phx5_HG_zoneb_u2

History list: phx5_HG_zoneb23May2014.bhst Format: extended Structure: non-regular Smooth: no Number of blocks: 324 Number of variables: 12 Number of schemas: 1 Origin: 476,725.0 6,373,800.0 30.0 Bearing/Dip/Plunge: 52.0 0. 0.0 Offset: 820.0 120.0 200.0

Model name: H:\PROJECTS\2299-Denison Mines Corp.-Phoenix Uranium Deposits\Work\Vulcan\Phoenix\phx5_LG_zonea_u2

History list: phx5_LG_zonea23May2014.bhst Format: extended Structure: non-regular Smooth: no Number of blocks: 5417 Number of variables: 12 Number of schemas: 1 Origin: 476,725.0 6,373,800.0 30.0 Bearing/Dip/Plunge: 52.0 0. 0.0 Offset: 820.0 120.0 200.0

Model name: H:\PROJECTS\2299-Denison Mines Corp.-Phoenix Uranium Deposits\Work\Vulcan\Phoenix\phx5_LG_zoneb_u2

History list: phx5_LG_zoneb23May2014.bhst Format: extended Structure: non-regular Smooth: no Number of blocks: 1506 Number of variables: 12 Number of schemas: 1 Origin: 476,725.0 6,373,800.0 30.0 Bearing/Dip/Plunge: 52.0 0. 0.0 Offset: 820.0 120.0 200.0

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Variables Default Type Description den -99.0 float density gxd_d -99.0 float gxd / den gxd -99.0 float grade (raw) x density grade_id2 -99.0 float interpolated raw grade ID2 grade_ok -99.0 Double interpolated grade ordinary kriging nsamp -99.0 short number of samples per estimate nholes -99.0 short number of holes per estimate strat unclass name stratigraphy nn -99.0 double nearest neighbor est_flag_id -99.0 integer estimation flag for ID est_flag_ok -99.0 integer estimation flag for OK ore -99.0 integer zones 1-13

PHOENIX DEPOSIT For zones A and B, blocks were five metres long along the main northeast trend, two metres

wide across the main trend, and one metre high. For the zone A basement domain, blocks

were two metres long along the main northeast trend, one metre wide across the main trend,

and one metre high. A whole block approach was used whereby the block was assigned to

the domain where its centroid was located.

The interpolation strategy involved setting up search parameters in two passes for each

domain. Search ellipses were oriented with the major axis oriented parallel to the dominant

northeasterly trend of the zones. The semi-major axis was oriented horizontally, normal to

the major axis (across strike) and the minor axis was vertical.

GxD and D were interpolated into the model using an initial pass. Blocks which did not

receive an interpolated grade were then interpolated in the second pass, which resulted in all

blocks being populated. Block grade was derived from the interpolated GxD value by

dividing that value by the interpolated density value for each block. Grades not weighted by

density (G) were also interpolated as a check.

In order to reduce the influence of very high grade composites, grades greater than a

designated threshold level for each domain were restricted to shorter search ellipse

dimensions. If the search ellipse contained a composite greater than the specified grade, it

was used for interpolation only if it fell within the restricted search ellipse. The threshold

grade levels were chosen from the basic statistics and from visual inspection of the apparent

continuity of very high grades within each domain.

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Search parameters are listed in Table 14-9 for the Phoenix deposit zones A and B, HG and

LG domains. Major axis is horizontal along the main mineralized trend of N52°E, semi-major

axis is horizontal normal to the main trend, and the minor axis is vertical.

TABLE 14-9 PHOENIX DEPOSIT BLOCK MODEL INTERPOLATION PARAMETERS


Deposit and Domain Pass Search Radii (m) Number of Composites Used

Major Semi-major Minor Min Max Max per

DH A Deposit HG First 35 15 8 3 8 2

Second 50 25 10 3 8 2 Restricted >60% U3O8 15 6 4 3 8 2

A Deposit LG First 35 15 8 3 8 2 Second 50 25 10 3 8 2

Restricted >6% U3O8 15 6 4 3 8 2 A Deposit Basement First 10 10 4 2 6 2


B Deposit HG First 35 15 6 3 8 2 Second 50 25 10 3 8 2

Restricted >40% U3O8 15 5 4 3 8 2 B Deposit LG First 35 15 6 3 8 2


Figure 14-17 is a three-dimensional isometric view looking downward to the north at the zone

A block model with colour coded grades. Higher grades are red and green. The blocks

shown are mostly in the LG domain. Figure 14-18 is an isometric view looking downward to

the north at the HG domain of the zone A block model with colour coded grades. Higher

grades are red and purple.

GRYPHON DEPOSIT Following the generation of the wireframes for each zone, the wireframes were filled by a

block model. The wireframes were used to assign domain codes to the blocks in the block

model and for generating and coding composited assays (Figure 14-19). RPA determined

that the 2 m by 10 m by 1 m block size was appropriate for modelling the individual

mineralized units.

ZONE A

Drill Hole Trace

Block Grade (U O %)3 8

< 0.001 %

0.001 % - 0.8 %

0.8 % - 5 %

5 % - 10 %

10 % - 20 %

20 % - 30 %

30 % - 50 %

> 50 %

0 25

Metres

50 75 100

N

November 2015


Phoenix Deposit Zone A3D Block Model

Denison Mines Corp.


Figure -1714

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ZONE A

Drill Hole Trace


< 0.001 %

0.001 % - 0.8 %

0.8 % - 5 %

5 % - 10 %

10 % - 20 %

20 % - 30 %

30 % - 50 %

> 50 %

0 25

Metres

50 75 100

N

November 2015


Phoenix Deposit Zone A3D HG Domain Block Model

Denison Mines Corp.


Figure -1814

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Zone A1

Zone C1


< 0. %05

0. % - 0.8 %2

0.8 % - 5 %

5 % - 10 %

10 % - 20 %

20 % - 30 %

30 % - 0 %6

> 0 %6

0. % - 0. %05 2

0 50

Metres

100 150 200

November 2015


Gryphon DepositBlock Model Domains A1 and C1

(Looking North)

Denison Mines Corp.


Figure 14-19

14-3

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Composited GxD values and D values were interpolated into each block model domain using

an ID2 algorithm for each mineralized domain. Domain boundaries were treated as hard

boundaries, so that composites from any given domain could not influence block grades in

other domains. Block grade was derived from the interpolated GxD value divided by the

interpolated D value for each block (GxD_D). Block tonnage was based on volume times the

interpolated D value.

The interpolation strategy involved setting up search parameters in two passes for each

individual mineralized wireframe. Table 14-10 provides a list of the estimation parameters

used for each pass, and all wireframes were subject to the same estimation parameters.

TABLE 14-10 GRYPHON BLOCK MODEL ESTIMATION PARAMETERS Denison Mines Corp. – Wheeler River Property

estimation_id flag_var flag_value alpha zeta beta major semi minor Min samples

Maxsamples dh_limit

id1_a1 est_flag_id 1 40 -30 -45 120 60 12 6 9 3 id1_a2 est_flag_id 1 40 -25 -45 120 60 12 2 6 2 id1_a3 est_flag_id 1 40 -25 -45 120 60 12 2 6 2 id1_b1 est_flag_id 1 40 -25 -45 120 60 12 6 9 3 id1_b2 est_flag_id 1 40 -25 -45 120 60 12 2 6 2 id1_b3 est_flag_id 1 40 -25 -45 120 60 12 3 9 3 id1_b4 est_flag_id 1 40 -25 -45 120 60 12 2 6 2 id1_c1 est_flag_id 1 40 -20 -40 120 60 12 6 9 3 id1_c2 est_flag_id 1 40 -20 -35 120 60 12 2 6 2 id1_d1 est_flag_id 1 40 -30 -45 120 60 12 2 4 2 id1_d2 est_flag_id 1 40 -30 -45 120 60 12 2 4 2 id1_d3 est_flag_id 1 40 -30 -45 120 60 12 2 4 2 id1_d4 est_flag_id 1 40 -30 -45 120 60 12 2 4 2 id2_a1 est_flag_id 2 40 -30 -45 120 60 12 2 4 2 id2_a2 est_flag_id 2 40 -25 -45 120 60 12 2 4 2 id2_a3 est_flag_id 2 40 -25 -45 120 60 12 2 4 2 id2_b1 est_flag_id 2 40 -25 -45 120 60 12 2 4 2 id2_b2 est_flag_id 2 40 -25 -45 120 60 12 2 4 2 id2_b3 est_flag_id 2 40 -25 -45 120 60 12 2 4 2 id2_b4 est_flag_id 2 40 -25 -45 120 60 12 2 4 2 id2_c1 est_flag_id 2 40 -20 -40 120 60 12 2 4 2 id2_c2 est_flag_id 2 40 -20 -35 120 60 12 2 4 2 id2_d1 est_flag_id 2 40 -30 -45 120 60 12 1 2 2 id2_d2 est_flag_id 2 40 -30 -45 120 60 12 1 2 2 id2_d3 est_flag_id 2 40 -30 -45 120 60 12 1 2 2 id2_d4 est_flag_id 2 40 -30 -45 120 60 12 1 2 2

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BLOCK MODEL VALIDATION The Phoenix and Gryphon deposit block models were validated by the following checks:

• Comparison of domain wireframe volumes with block volumes.

• Visual comparison of composite grades with block grades.

• Comparison of block grades with composite grades used to interpolate grades.

• Comparison with estimation by a different method.

In RPA’s opinion, block model validation is reasonable and acceptable.

VOLUME COMPARISON Wireframe volumes were compared to block volumes for each domain at the Phoenix and

Gryphon deposits. This comparison is summarized in Table 14-11 and results show that

there is good agreement between the wireframe volumes and block model volume. The

difference is less than 2%, except for the zone B HG, A3, and B2 domains where the

difference ranges from 3.5% to 6% due to the small volume of the wireframe combined with

the whole block approach.

TABLE 14-11 VOLUME COMPARISON FOR WIREFRAME AND BLOCKS BY DOMAIN

Denison Mines Corp. – Wheeler River Project

Deposit and Zone Wireframe Block Model %

Difference Points Triangles SurfaceArea

Volume (m3) Blocks Volume

(m3) Phoenix Deposit Zone A HG 4,965 9,926 16,732 17,999 1,808 18,080 0.45% Zone A LG 13,313 26,682 49,758 54,270 5,416 54,160 -0.20% Zone B HG 308 612 3,722 3,109 324 3,240 4.05% Zone B LG 1,604 3,254 14,911 15,142 1,492 14,920 -1.49% Zone A Basement 132 260 2009 2 1,115 2,230 -1.02%

Gryphon Deposit A1 783 1,562 101,254 172,570 8614 172,280 0.17% A2 770 1,536 76,882 86,959 4346 86,920 0.04% A3 206 404 22,676 20,305 955 19,100 5.94% B1 589 1,174 73,444 101,644 5156 103,120 -1.45% B2 268 532 32,089 38,599 1861 37,220 3.57% B3 82 160 11,205 14,929 762 15,240 -2.08% C1 343 682 31,363 33,766 1648 32,960 2.39% C2 267 530 23,213 21,189 1053 21,060 0.61%

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VISUAL COMPARISON Block grades were visually compared with drill hole composites on cross sections,

longitudinal sections, and plan views. The block grades and composite grades correlate very

well visually within both the Phoenix and Gryphon deposits.

STATISTICAL COMPARISON Statistics of the block grades are compared with statistics of composite grades in Table 14-

12 for all blocks and composites within the Phoenix deposit zones A and B, HG, and LG

domains. Table 14-13 lists the composites versus block grades for Gryphon. Grades are

weighted by density for the composites and tonnage for the blocks. In some cases, the

average block grades are higher than the average composite grades, which RPA attributes

to density weighting of the block grades or distribution of the drill holes within relatively small

zones.

TABLE 14-12 STATISTICS OF BLOCK GRADES COMPARED TO COMPOSITE GRADES BY DOMAIN - PHOENIX


Statistic Zone A HG Zone A LG Zone A BSMT Zone B HG Zone B LG

Blocks Comps Blocks Comps Blocks Comps Blocks Comps Blocks Comps Mean (%U3O8) 39.18 34.86 1.73 1.77 1.35 1.56 25.71 21.65 1.34 1.57

Standard Error 0.37 1.93 0.02 0.14 0.35 0.36 0.59 3.74 0.04 0.31

Median (%U3O8) 36.51 31.52 1.22 0.59 0.14 0.32 26.63 17.14 0.69 0.53

Mode (%U3O8) N/A N/A 0.44 0.18 0.00 0.00 N/A N/A N/A 0.25 Standard Deviation

(%U3O8) 15.63 21.62 1.72 2.69 4.11 4.26 10.66 15.85 1.65 2.64

Sample Variance 244.16 467.56 2.98 7.23 16.91 18.12 113.73 251.25 2.71 6.99

Kurtosis -0.13 -0.69 16.02 10.25 25.63 23.16 -1.18 -1.02 5.04 4.65

Skewness 0.67 0.45 3.05 2.81 4.90 4.72 -0.08 0.54 2.23 2.36

Range (%U3O8) 77.76 82.31 19.85 20.13 27.82 27.66 44.86 49.24 10.48 10.86

Min (%U3O8) 4.62 0.29 0.03 0.01 0.00 0.00 3.46 1.46 0.01 0.01

Max (%U3O8) 82.38 82.60 19.88 20.14 27.82 27.66 48.32 50.69 10.49 10.87

Sum 70,832 4,357 9,354 608 186.78 215 8,329 390 2,025 113

Count 1,808 125 5,417 344 138 138 324 18 1,506 72 Coefficient of

Variation 0.40 0.62 1.00 1.52 3.04 2.73 0.41 0.73 1.23 1.68

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TABLE 14-13 STATISTICS OF BLOCK GRADES COMPARED TO COMPOSITE GRADES BY DOMAIN - GRYPHON


Statistic Zone A1 Zone A2 Zone A3 Zone B1

Comps Blocks Comp Blocks Comp Blocks Comp Blocks Count 131 8,486 51 3,528 4 398 51 3,219 Mean 2.25 2.72 0.76 0.88 0.94 0.97 0.89 1.34 Median 0.38 1.51 0.16 0.52 0.67 0.99 0.18 0.87 Std. Dev. 4.53 2.89 1.32 0.92 0.96 0.22 2.34 1.31 Variance 20.52 8.34 1.74 0.84 0.92 0.05 5.46 1.71 Kurtosis 12.36 5.48 3.74 2.12 -1.28 0.39 16.26 3.40 Skewness 3.26 2.00 2.16 1.59 0.55 0.46 4.10 1.68 Range 30.00 25.47 5.43 5.06 2.42 1.32 12.34 9.90 Minimum 0.00 0.05 0.00 0.05 0.00 0.47 0.00 0.05 Maximum 30.00 25.52 5.43 5.11 2.42 1.78 12.34 9.95 Coef. of Var. 2.02 1.06 1.74 1.04 1.02 0.23 2.64 0.98

Statistic Zone B2 Zone B3 Zone C1 Zone C2

Comp Blocks Comp Blocks Comps Blocks Comp Blocks Count 26 1,757 15 580 26 1,513 15 454 Mean 2.33 1.72 2.76 3.94 3.48 3.13 0.19 0.18 Median 0.33 0.74 0.44 2.18 0.56 1.38 0.01 0.10 Std. Dev. 3.85 2.03 4.45 4.17 6.70 4.14 0.35 0.21 Variance 14.81 4.14 19.84 17.43 44.90 17.13 0.12 0.04 Kurtosis 1.97 2.50 1.46 -0.71 3.15 4.04 5.94 6.48 Skewness 1.81 1.75 1.67 0.87 2.16 2.09 2.56 2.66 Range 13.54 9.77 14.77 14.98 24.03 22.08 1.39 1.11 Minimum 0.00 0.05 0.00 0.11 0.00 0.07 0.00 0.05 Maximum 13.54 9.82 14.77 15.10 24.03 22.15 1.39 1.17 Coef. of Var. 1.65 1.18 1.61 1.06 1.92 1.32 1.83 1.15

CHECK BY DIFFERENT ESTIMATION METHODS PHOENIX DEPOSIT RPA has carried out check estimates of the Denison ID2 block models of the Phoenix deposit

using the contour method.

For the contour method (Agnerian and Roscoe, 2002), grade times thickness times density

(GxTxD) values for each drill hole intercept were plotted on plans and contoured. The areas

between the contours were measured and multiplied by the average value in the contour

interval. The GxTxD values are proportional to pounds of U3O8 per square metre and the

sum of these values times area are converted to total pounds of U3O8 for each domain.

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Thickness times density (TxD) values were also plotted on plans and contoured. The areas

between the contours were measured and multiplied by the average value in the contour

interval. The sum of the TxD values multiplied by the area represents tonnage for each of

the domains. For the contour method check on the Phoenix deposit zone A HG domain, the

tonnes, grade, and contained pounds of U3O8 estimated by the contour method are in the

same general range as the ID2 block model estimate.

CUT-OFF GRADE

PHOENIX DEPOSIT The cut-off grade of 0.8% U3O8 is based on internal conceptual studies by Denison and a

price of US$50/lb U3O8. The HG domains are not sensitive to cut-off grades less than 5%

U3O8 while the LG domains are quite sensitive to cut-off grade. RPA recommends that the

cut-off grade should be revisited during future resource estimations on the Phoenix deposit.

Table 14-14 and Figure 14-20 show the sensitivity of the Indicated Mineral Resource to cut-

off grade. It can be seen that, although there is some sensitivity of the tonnes and grade to

cut-off grade, the contained pounds of U3O8 are much less sensitive to cut-off grade. The

cut-off grade affects essentially only the LG domains of zones A and B because virtually all

of the blocks in the HG domains of zones A and B are above the 5% U3O8 cut-off grade.

TABLE 14-14 PHOENIX DEPOSIT INDICATED MINERAL RESOURCE SENSITIVITY TO CUT-OFF GRADE


Cut-off % U3O8

Grade % U3O8

Tonnes Lb U3O8 Millions

0.50 16.94 188,900 70.5 0.80 19.13 166,200 70.2 1.00 20.60 154,000 69.9 1.50 24.23 129,800 69.3 2.00 27.40 113,700 68.7 3.00 32.42 94,700 67.7 5.00 38.07 79,100 66.3

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FIGURE 14-20 PHOENIX INDICATED MINERAL RESOURCE TONNES AND GRADE AT VARIOUS CUT-OFF GRADES

GRYPHON DEPOSIT RPA estimated a potential underground mining cut-off grade using assumptions based on

historical and known operating costs on mines operating in the Athabasca Basin. Table 14-

15 shows the breakeven cut-off grade estimate by RPA using a price of US$50/lb U3O8 and

based on assumptions for process plant recovery, total operating cost, and incremental

component of operating cost. The estimated cut-off grade of 0.2% U3O8 is in line with the

cut-off grade of 0.2% that RPA understands is used at Cameco’s Rabbit Lake mine, which is

basement mineralization similar geologically to Gryphon.

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

60,000

80,000

100,000

120,000

140,000

160,000

180,000

200,000

220,000

0.0 1.0 2.0 3.0 4.0 5.0 6.0

Aver

age

Gra

de (%

U3O

8)

Tonn

es

Cut-off Grade % U3O8

Phoenix Grade vs. Tonnes

Tonnes Avg. Grade

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TABLE 14-15 GRYPHON DEPOSIT CUT-OFF GRADE CALCULATION Denison Mines Corp. – Wheeler River Property

Item Quantity Price in US$/lb U3O8 US$50 Process plant recovery 90% Operating cost per tonne US$270 Incremental operating cost component (75%) US$200 Cut-off grade 0.2%

Table 14-16 and Figure 14-21 show the sensitivity of the Gryphon block model to various cut-

off grades. RPA notes that, although there is some sensitivity of average grade and tonnes

to cut-off grade, the contained ounces are less sensitive.

TABLE 14-16 GRYPHON DEPOSIT INFERRED MINERAL RESOURCE SENSITIVITY TO CUT-OFF GRADE


Cut-off % U3O8

Grade % U3O8

Tonnes (000)

Mlb U3O8

0.20 2.342 834 43 0.40 2.679 716 42 0.60 2.981 629 41 0.80 3.367 538 40 1.00 3.701 474 39

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FIGURE 14-21 GRYPHON INFERRED MINERAL RESOURCE TONNES AND GRADE AT VARIOUS CUT-OFF GRADES

CLASSIFICATION Definitions for resource categories used in this report are consistent with those in the CIM

(2014) and adopted by NI 43-101. In CIM (2014), a Mineral Resource is defined as “a

concentration or occurrence of solid material of economic interest in or on the Earth’s crust in

such form, grade or quality and quantity that there are reasonable prospects for eventual

economic extraction”. Mineral Resources are classified into Measured, Indicated, and

Inferred categories. A Mineral Reserve is defined as the “economically mineable part of a

Measured and/or Indicated Mineral Resource” demonstrated by studies at Pre-Feasibility or

Feasibility level as appropriate. Mineral Reserves are classified into Proven and Probable

categories. No Mineral Reserves have been estimated for the Property.

PHOENIX DEPOSIT The Mineral Resources for the Phoenix deposit are classified as Indicated and Inferred

based on drill hole spacing and apparent continuity of mineralization.

0.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

0

100,000

200,000

300,000

400,000

500,000

600,000

700,000

800,000

900,000

0.0 0.2 0.4 0.6 0.8 1.0 1.2

Aver

age

Gra

de (%

U3O

8)

Tonn

es

Cut-off Grade % U3O8

Gryphon Grade vs. Tonnes

Tonnes Avg. Grade

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At zone A, the drill hole spacing is approximately 10 m on sections spaced 25 m apart. The

classification of Indicated based on drill hole density and good grade continuity along strike is

appropriate in RPA’s opinion for all of the LG and HG domains. The zone A basement

domain is classified as Inferred because of uncertainty of grade continuity due to the small

number of drill holes.

At zone B, the drill hole spacing is approximately 10 m on sections spaced 25 m apart. The

classification of Indicated is appropriate in RPA’s opinion for most of the LG and HG

domains. In the northeastern part of zone B, drill hole sections are spaced at approximately

35 m and the most northeasterly drill hole does not correlate well spatially with other drill

holes because its elevation is slightly lower. This part of zone B is classified as Inferred

because there is some uncertainty in the continuity of grade in both the HG and LG domains.

Figure 14-22 shows the area of Inferred Mineral Resources along with Indicated Mineral

Resources at zone B.

GRYPHON DEPOSIT The Mineral Resources for the Gryphon deposit are classified as Inferred based on drill hole

spacing and apparent continuity of mineralization.

Drill Hole Trace

ZONE B1

ZONE B2

Indicated Resource

Inferred Resource

High Grade Domain (solid filled)

Infe

rred

Boundary

Low Grade Domain (non-filled)Indicated Resource

N


< 0.001 %

0.001 % - 0.8 %

0.8 % - 5 %

5 % - 10 %

10 % - 20 %

20 % - 30 %

30 % - 50 %

> 50 %

0 25

Metres

50 75 100

UTM Projection WGS 84-13N

November 2015


Phoenix Deposit Zone BBlock Model Showing Inferred

and Indicated Resources

Denison Mines Corp.


Figure 2214-

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MINERAL RESOURCE ESTIMATE Table 14-17 lists the Mineral Resource estimate for the Wheeler River Property by domain

and resource category. The effective date of the resource estimate is September 25, 2015.

The Phoenix cut-off grade of 0.8% U3O8 is based on internal conceptual studies by Denison

and a price of US$50/lb U3O8, while a cut-off grade of 0.2% U3O8 for Gryphon is based on

RPA estimates using assumptions based on historical and known mining costs on mines

operating in the Athabasca Basin at a price of US50/lb U3O8.

For the Phoenix and Gryphon deposits, total Indicated Mineral Resources are estimated at

166,400 tonnes at an average grade of 19.13% U3O8 containing 70.2 million pounds of U3O8.

Total Inferred Mineral Resources are estimated at 842,600 tonnes at an average grade of

2.37% U3O8 containing 44.1 million pounds of U3O8.

In RPA’s opinion, the estimation methodology is consistent with standard industry practice

and the Wheeler River Property Mineral Resource estimate is considered to be reasonable

and acceptable.

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TABLE 14-17 MINERAL RESOURCE ESTIMATE FOR THE WHEELER RIVER PROJECT AS OF SEPTEMBER 25, 2015


Category Deposit and Domain Tonnes Grade (% U3O8)

Contained Metal (million lb U3O8)

Indicated Phoenix Zone A HG 62,900 43.24 59.9 Indicated Phoenix Zone A LG 84,300 2.37 4.4 Indicated Phoenix Zone B HG 8,500 28.02 5.2 Indicated Phoenix Zone B LG 10,700 2.91 0.7 Subtotal Indicated Phoenix Zone A 147,200 19.81 64.3 Subtotal Indicated Phoenix Zone B 19,200 13.94 5.9 Total Indicated 166,400 19.13 70.2

Inferred Phoenix Zone A HG 0 0 0 Inferred Phoenix Zone B HG 700 14.48 0.2 Inferred Phoenix Zone B LG 4,800 1.79 0.2 Inferred Phoenix Zone A Basement 3,100 10.24 0.7 Subtotal Inferred Phoenix Zone A 0 0 0.0 Subtotal Inferred Phoenix Zone B 5,500 3.30 0.4 Subtotal Inferred Phoenix Zone A Basement 3,100 10.24 0.7 Subtotal Inferred Phoenix Deposit 8,600 5.80 1.1 Inferred Gryphon A1 387,200 2.89 24.6 Inferred Gryphon A2 125,200 1.10 3.0 Inferred Gryphon A3 18,100 0.97 0.4 Inferred Gryphon B1 137,500 1.43 4.3 Inferred Gryphon B2 73,300 1.90 3.1 Inferred Gryphon B3 19,000 5.72 2.4 Inferred Gryphon C1 69,700 3.33 5.1 Inferred Gryphon C2 3,900 0.54 0.1 Subtotal Inferred Gryphon Deposit 834,000 2.37 43.0 Total Inferred Phoenix and Gryphon 842,600 2.37 44.1

Notes:



assumptions and a price of US$50 per lb U3O8. 4. High grade composites are subjected to a high grade search restriction without capping at Phoenix. 5. High grade mineralization was capped at 30% with no search restrictions at Gryphon. 6. Bulk density is derived from grade using a formula based on 196 measurements at Phoenix and 65


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15 MINERAL RESERVE ESTIMATE There is no current Mineral Reserve estimate on the Gryphon deposit.

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16 MINING METHODS This section is not applicable.

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17 RECOVERY METHODS This section is not applicable.

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18 PROJECT INFRASTRUCTURE This section is not applicable.

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19 MARKET STUDIES AND CONTRACTS This section is not applicable.

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20 ENVIRONMENTAL STUDIES, PERMITTING, AND SOCIAL OR COMMUNITY IMPACT This section is not applicable.

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21 CAPITAL AND OPERATING COSTS This section is not applicable.

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22 ECONOMIC ANALYSIS This section is not applicable.

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23 ADJACENT PROPERTIES This section is not applicable.

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24 OTHER RELEVANT DATA AND INFORMATION This section is not applicable.

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25 INTERPRETATION AND CONCLUSIONS Drilling at the Wheeler River Property from 2008 to 2014 discovered and delineated the

Phoenix uranium deposit at the intersection of the Athabasca sandstone basal unconformity

with a regional fault zone, the WS fault, and graphitic pelite basement rocks. Drilling from

2014 to 2015 discovered the basement hosted Gryphon uranium deposit located

approximately three kilometres northwest of the Phoenix deposit.

The Phoenix deposit consists of two separate lenses known as zone A and zone B located at

the Athabasca unconformity approximately 400 m below surface within a one kilometre long,

northeast trending mineralized corridor. Both lenses contain a higher grade core within a

lower grade mineralized envelope and extend southeastward from the WS fault along the

unconformity. Some mineralization also occurs on the northwest side of the WS fault but

commonly at a slightly lower elevation. In addition to zones A and B, a domain of uranium

mineralization below and adjacent to zone A has been identified in basement rocks (zone A

basement) and included in this report.

Mineral Resources for Phoenix, based on 196 diamond drill holes totalling 89,835 m, were

estimated by RPA. Indicated Resources total 166,400 t at 19.13% U3O8 containing 70.2

million lb U3O8. Inferred Resources total 8,600 t at 5.80% U3O8 containing 1.1 million lb

U3O8.

Mineralization at the Gryphon deposit, located three kilometres northwest of Phoenix, occurs

in basement rocks approximately 200 m beneath the Athabasca sandstone unconformity. In

this area, the unconformity drops to the northwest in a series of reverse fault offsets.

Cumulative offset is approximately 60 m of vertical displacement over 250 m across strike.

Basement rocks are Wollaston Group gneisses that dip moderately to the southeast and

consist of an upper graphitic pelite unit overlying a quartzite/pegmatite assemblage which

overlies a lower graphitic pelite unit followed by a basal pegmatite. To date, the

mineralization is hosted in fault zones at the base of the upper graphitic pelite and within the

lower graphitic pelite. The faults are assumed to dip moderately to the southeast,

conformable with the bedding and foliation in the basement rocks.

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Mineral Resources for Gryphon, based on 55 diamond drill holes totalling 40,041 m, were

estimated by RPA. Inferred Resources total 834,000 t at 2.31% U3O8 containing 43.0 million

lb U3O8. In RPA’s opinion, additional infill drilling on 25 m profile spacing or wedging off of

current drill holes would be needed to bring the Inferred Mineral Resource into Indicated

status.

In RPA’s opinion, a Preliminary Economic Assessment (PEA) could be carried out on the

Phoenix and Gryphon deposits combined.

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26 RECOMMENDATIONS In the third quarter of 2015, the Wheeler River Joint Venture commenced a PEA. At the end

of the PEA, a review of the project will be completed with recommendations for next steps.

Should the project proceed into pre-feasibility, initial work will focus on environmental

baseline studies, engineering field programs, and engineering studies.

The Wheeler River Joint Venture plans to continue exploration on the Property in 2016, with

emphasis expected to be on the areas to the northeast and southwest of Gryphon, as well as

other targets on the Property. In addition, an infill drilling program may be undertaken on the

Gryphon deposit to bring the Inferred Mineral Resource into Indicated status if warranted by

positive PEA results.

RPA has reviewed the preliminary plans for 2016 and concurs with the program planned for

the Wheeler River Joint Venture in 2016. Denison’s 2016 budget for the Wheeler River Joint

Venture has not been disclosed yet, but RPA expects exploration expenditures to be in the

order of C$10 million. Contingent on results of this program and the PEA, a second phase

will consist of infill drilling at Gryphon, environmental baseline studies, engineering field

programs, and engineering studies as part of the initiation of a pre-feasibility study. RPA

expects that the cost of the second phase program will be in the order of C$3 million.

If further drilling is completed at Gryphon, RPA recommends that Denison continue to collect

additional bulk density data to increase the confidence of estimated densities of the entire

grade range.

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27 REFERENCES Agnerian, H., and W. E. Roscoe, 2002: The Contour Method of Estimating Mineral

Resources. CIM Bulletin, v. 95, pp. 100-107. Arseneau, G., and C. Revering, 2010, Technical Report on the Phoenix Deposit (Zones A &

B) – Wheeler River Project, Eastern Athabasca Basin, Northern Saskatchewan, Canada, SRK Consulting (Canada) Inc. NI 43-101 Technical Report for Denison Mines Corp. (November 17, 2010).

Bosman, S.A., and J. Korness, 2007: Building Athabasca Stratigraphy, Revising, redefining,

and Repositioning. in Summary of Investigations, Volume 2, Saskatchewan Geological Survey, Saskatchewan Ministry of Energy and Resources, Miscellaneous Report 2007-4.2, CD-ROM, Paper A-8, 29 p.

Campbell, J.E., 2007: Quaternary geology of the eastern Athabasca Basin, Saskatchewan in

Jefferson, C.W. and Delaney, G. eds., EXTECH IV: Geology and Uranium Exploration Technology of the Proterozoic Athabasca Basin, Saskatchewan and Alberta, Geological Survey of Canada Bulletin 588, pp. 211-228.

Canadian Institute of Mining, Metallurgy and Petroleum (CIM), 2014: CIM Definition

Standards for Mineral Resources and Mineral Reserves, adopted by the CIM Council on May 10, 2014.

Card, C.D., D. Pana, P. Portella, D.J. Thomas, and I.R. Annelsey, 2007: Basement rocks of

the Athabasca Basin, Saskatchewan and Alberta in Jefferson, C.W. and Delaney, G. eds., EXTECH IV: Geology and Uranium Exploration Technology of the Proterozoic Athabasca Basin, Saskatchewan and Alberta, Geological Survey of Canada Bulletin 588, pp. 69-87.

Dahlkamp, F.J., and B. Tan, 2007: Geology and mineralogy of the Key Lake U-Ni deposits,

northern Saskatchewan, Canada in Jones, M.J. eds., Geology, Mining, and Extractive Processing of Uranium: Institute of Mining and Metallurgy, London, pp. 145-157.

Denison Mines Corp., 2009-2011: Various Internal QA/QC Procedures and Memos outlining core logging, sampling, borehole logging, etc. Denver, Saskatoon.

Earle, S., and V. Sopuck, 1989: Regional lithogeochemistry of the eastern part of the

Athabasca Basin uranium province in Uranium Resources and Geology of North America, International Atomic Energy Agency-TecDoc-500, pp. 263-296.

Gyorfi, I., 2006: Seismic constraints on the geological evolution of the McArthur River region

in view of the tectonics of the western Athabasca Basin, northern Saskatchewan. PhD Thesis, Saskatchewan: University of Saskatchewan, 230 p.

Hanly, A.J., 2001: The Mineralogy, Petrology and Rare Earth Element Geochemistry of the

MAW Zone, Athabasca Basin, Canada. Unpublished M.Sc. Thesis, Rolla, Missouri, USA: University of Missouri-Rolla, 168 p.

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Jefferson, C.W., D.J. Thomas, S.S. Gandhi, P. Ramaekers, and et al., 2007: Unconformity-associated uranium deposits of the Athabasca Basin, Saskatchewan and Alberta in Jefferson, C.W. and Delaney, G. eds., EXTECH IV: Geology and Uranium Exploration Technology of the Proterozoic Athabasca Basin, Saskatchewan and Alberta, Geological Survey of Canada Bulletin 588, pp. 23-67.

Kerr, W.C., 2010: The Discovery of the Phoenix Deposit: a New High Grade, Athabasca

Basin Unconformity-Type Uranium Deposit, Saskatchewan, Canada. Society of Economic Geologists Special Publications 15, pp. 703-728.

Kerr, W.C., C. Gamelin, C. Sorba, R. Basnett, L. Petrie, and R. Wallis, 2011: The Phoenix

Deposits: New High-Grade, Athabasca Basin Unconformity-Type Uranium Deposits, Saskatchewan, Canada. Vienna Paper Version #7, 45 p.

Liu, Y., K. Bodnarchuk, L. Petrie, and R. Basnett, 2011: Wheeler River Project, Denison

Mines Corp., 87 p. McGill, D.G., J.L. Marlat, R.G. Matthews, V.J. Supuck, L.A. Homeniuk, and J.J Hubregtse,

2993: The P2 North uranium deposit, Saskatchewan, Canada, Exploration and Mining Geology, v. 2, pp. 321-331.

Quirt, D.H., 2003: Athabasca unconformity-type uranium deposits: one deposit type with

many variations. Uranium Geochemistry 2003, International Conference, Nancy, France, April 13-16 2003, Proceedings, pp. 309-312.

Ramaekers, P., et al., 2007: Revised geological map and stratigraphy of the Athabasca

Group, Saskatchewan and Alberta in Jefferson, C.W. and Delaney, G. eds., EXTECH IV: Geology and Uranium Exploration Technology of the Proterozoic Athabasca Basin, Saskatchewan and Alberta, Geological Survey of Canada Bulletin 588, pp. 151-191.

Roscoe, W E., 2014: Technical Report on a Mineral Resource Estimate Update for the

Phoenix Uranium Deposit, Wheeler River Project, Eastern Athabasca Basin, Northern Saskatchewan, Canada, RPA NI 43-101 Report prepared for Denison Mines Corp. (June 17, 2014).

Roscoe, W.E., 2012: Technical Report on a Mineral Resource Estimate Update for the

Phoenix Uranium Deposits, Wheeler River Project, Eastern Athabasca Basin, Northern Saskatchewan, Canada, RPA NI 43-101 Report prepared for Denison Mines Corp. (December 31, 2012).

Saracoglu, N., R.H. Wallis, J.J. Brummer, and J.P. Golightly, 1983: The McClean uranium

deposits, northern Saskatchewan discovery, Canadian Mining and Metallurgical Bulletin, V. 76, No. 852, pp. 63-79.

Sweet, K., and T. McEwan, 2011: Discussion of probe quality and grade evaluation Dibwe-

Mutanga Project, KenCo Minerals internal report for Denison Mines Zambia Limited. Sweet, K.O., and L. Petrie, 2010: Denison Memo on calibration factor for triple gamma

probe. Memorandum, Internal Denison Mines Corp. report.

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Wallis, R.H., N. Saracoglu, J.J. Brummer, and J.P. Golightly, 1984: The geology of the McClean uranium deposits, northern Saskatchewan, Canadian Mining and Metallurgical Bulletin, V. 77, No. 864, pp. 69-96.

Wasyliuk, K., 2002: Petrogenesis of the kaolinite-group minerals in the eastern Athabasca

basin of northern Saskatchewan: applications to uranium mineralization. Unpublished M.Sc. Thesis, Saskatoon, Canada: University of Saskatchewan, 140 p.

Yeo, G.M., and G. Delaney, 2007: The Wollaston Supergroup, stratigraphy and metallogeny

of a Paleoproterozoic Wilson cycle in the Trans-Hudson Orogeny, Saskatchewan in Jefferson, C.W. and Delaney, G. eds., EXTECH IV: Geology and Uranium Exploration Technology of the Proterozoic Athabasca Basin, Saskatchewan and Alberta, Geological Survey of Canada Bulletin 588, pp. 89-117.

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28 DATE AND SIGNATURE PAGE This report titled “Technical Report on a Mineral Resource Estimate for the Wheeler River

Property, Eastern Athabasca Basin, Northern Saskatchewan, Canada” and dated November

25, 2015, was prepared and signed by the following authors:

(Signed & Sealed) “William E. Roscoe” Dated at Toronto, ON November 25, 2015 William E. Roscoe, Ph.D., P.Eng. Principal Geologist (Signed & Sealed) “Mark B. Mathisen” Dated at Lakewood, CO November 25, 2015 Mark B. Mathisen, C.P.G. Senior Geologist

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29 CERTIFICATE OF QUALIFIED PERSON WILLIAM E. ROSCOE I, William E. Roscoe, Ph.D., P.Eng., as an author of this report entitled “Technical Report on a Mineral Resource Estimate for the Wheeler River Property, Eastern Athabasca Basin, Northern Saskatchewan, Canada”, prepared for Denison Mines Corp. (the “Issuer”), and dated November 25, 2015, do hereby certify that:

1. I am a Principal Geologist with Roscoe Postle Associates Inc. of Suite 501, 55 University Ave Toronto, ON, M5J 2H7.

2. I am a graduate of Queen’s University, Kingston, Ontario, in 1966 with a Bachelor of

Science degree in Geological Engineering, McGill University, Montreal, Quebec, in 1969 with a Master of Science degree in Geological Sciences and in 1973 a Ph.D. degree in Geological Sciences.

3. I am registered as a Professional Engineer (No. 39633011) and designated as a

Consulting Engineer in the Province of Ontario. I have worked as a geologist for a total of 46 years since my graduation. My relevant experience for the purpose of the Technical Report is: • Thirty-one years of experience as a Consulting Geologist across Canada and in

many other countries • Preparation of numerous reviews and technical reports on exploration and mining

projects around the world for due diligence and regulatory requirements • Senior Geologist in charge of mineral exploration in southern Ontario and

Québec • Exploration Geologist with a major Canadian mining company in charge of

exploration projects in New Brunswick, Nova Scotia, and Newfoundland

4. I have read the definition of "qualified person" set out in National Instrument 43-101 (NI 43-101) and certify that by reason of my education, affiliation with a professional association (as defined in NI 43-101) and past relevant work experience, I fulfill the requirements to be a "qualified person" for the purposes of NI 43-101.

5. I visited the Wheeler River Project on October 30, 2012, and June 16, 2014.

6. I share responsibility with my co-author for all of the sections of the Technical Report.

7. I am independent of the Issuer applying the test set out in Section 1.5 of NI 43-101.

8. I have previously authored a NI 43-101 Technical Report on the property (Phoenix deposit) that is the subject of the Technical Report.

9. I have read NI 43-101 and this Technical Report, and the Technical Report has been prepared in compliance with NI 43-101 and Form 43-101F1.

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10. At the effective date of the Technical Report, to the best of my knowledge, information, and belief, the Technical Report contains all scientific and technical information that is required to be disclosed to make the Technical Report not misleading.

Dated this 25th day of November, 2015 (Signed & Sealed) “William E. Roscoe” William E. Roscoe, Ph.D., P.Eng.

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MARK B. MATHISEN I, Mark B. Mathisen, CPG, as an author of this report entitled “Technical Report on a Mineral Resource Estimate for the Wheeler River Property, Eastern Athabasca Basin, Northern Saskatchewan, Canada”, prepared for Denison Mines Corp. (the “Issuer”), and dated November 25, 2015, do hereby certify that: 1. I am Senior Geologist with RPA (USA) Ltd. of Suite 505, 143 Union Boulevard,

Lakewood, Co., USA 80228. 2. I am a graduate of Colorado School of Mines in 1984 with a B.Sc. degree in Geophysical

Engineering. 3. I am a Registered Professional Geologist in the State of Wyoming (No. PG-2821) and a

Certified Professional Geologist with the American Institute of Professional Geologists (No. CPG-11648). I have worked as a geologist for a total of 20 years since my graduation. My relevant experience for the purpose of the Technical Report is: • Mineral Resource estimation and preparation of NI 43-101 Technical Reports. • Director, Project Resources, with Denison Mines Corp., responsible for resource

evaluation and reporting for uranium projects in the USA, Canada, Africa, and Mongolia.

• Project Geologist with Energy Fuels Nuclear, Inc., responsible for planning and direction of field activities and project development for an in situ leach uranium project in the USA. Cost analysis software development.

• Design and direction of geophysical programs for US and international base metal and gold exploration joint venture programs.

4. I have read the definition of "qualified person" set out in National Instrument 43-101 (NI

43-101) and certify that by reason of my education, affiliation with a professional association (as defined in NI 43-101) and past relevant work experience, I fulfill the requirements to be a "qualified person" for the purposes of NI 43-101.

5. I visited the Wheeler River Property on March 23 to 25, 2015. 6. I share responsibility with my co-author for all of the sections of the Technical Report. 7. I am independent of the Issuer applying the test set out in Section 1.5 of NI 43-101. 8. I was working on the database QA/QC for Gryphon between late 2013 and April 2014.

First resource modelling for Gryphon was done after I joined RPA in May 2014. 9. I have read NI 43-101, and the Technical Report has been prepared in compliance with

NI 43-101 and Form 43-101F1.

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10. At the effective date of the Technical Report, to the best of my knowledge, information, and belief, the Technical Report contains all scientific and technical information that is required to be disclosed to make the Technical Report not misleading.

Dated this 25th day of November, 2015 (Signed & Sealed) “Mark B. Mathisen” Mark B. Mathisen

Documents

DENISON MINES CORP. TECHNICAL REPORT ON A MINERAL … · updated in a NI 43101 Technical Report dated June 17, 2014 (the 2014 Phoenix Report)- and authored by William E. Roscoe, Ph.D.,